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Welcome to the pmean blog. Please note that pmean is short for Professor Mean, my alter-ego on the Internet. My real name is Steve Simon.

This site has over 2,200 files covering statistical analysis, research ethics, and evidence-based medicine. It’s a bit of a rat’s nest, to be honest, with simple tutorial pages for total beginners to very technical pages for advanced audiences. It is also in transition from an earlier version of my website.

You can find earlier entries at

Some of the pages on these sites are completely broken, partially broken, have missing images, etc. My goal is to use the new site to fix up every bad page and crosslink those files to the old ones. With over 2,200 pages, this will take a while. Refer to the [about page] to get a bit more information about the older sites.

I also have an early draft of a book, Jump Start Statistics

New web recommendation

This is the class materials for a course on data visualization. It covers a lot of the psychology behind perception and offers a lot of code using the ggplot2 library of R.…

The Dataverse Project

*Recommendation

Year 2026

Data Sharing

The dataverse project is a software system that automates the process of developing sharable research data resources.

Statistical Tests, Tests of Significance, and Tests of a Hypothesis Using Excel

*Recommendation

Year 2026

Numerical Accuracy

A detailed examination of accuracy issues for Excel, but this paper also provides general guidance on the computational details associated with loss of statistical accuracy.

Some options for the yaml header in Quarto

Blog post

I have been using Quarto for a couple of years now and I really like it. I wanted to document a few options that I like for the yaml header in a Quarto file.

When do you need to address non-linearity?

*Blog post

2025

Ask Professor Mean

Linear regression

Dear Professor Mean,

How should I start coding?

*Blog post

2025

Ask Professor Mean

R software

Dear Professor Mean,

When should you use a weighted mean?

*Blog post

2025

Ask Professor Mean

Complex surveys

Descriptive statistics

Dear Professor Mean,

Relevant survival numbers

*Recommendation

Year 2025

Survival analysis

While the hazard ratio is difficult to interpret, there are, according to Stephen Senn, problems with the alternatives (median survival time and probability of surviving to…

Consistent sizing of your boxplots

I wanted to show a series of boxplots comparing how a continuous outcome changes for different levels of a categorical variable. The categorical variable sometimes had two…

The mathematical foundations of the two sample t-test

*Blog post

2025

Being updated

A student wanted to know a bit more about the mathematical foundations of the two sample t-test. Without getting too deep into the mathematics (meaning that I can’t invoke…

The analysis of variance table in a linear regression model

*Blog post

Linear regression

The analysis of variance table is used for an analysis of variance model, but it is also used for a linear regression model. I want to offer some intuition on what all the…

Scientific data

*Recommendation

Year 2025

Datasets

This journal is devoted to documenting datasets of great scientific or medical importance. They also have articles about the policies, standards, and mechanics of data…

A big milestone for quarto

*Blog post

Website details

Over the 27 years that this website has been in existence, I have used a variety of different software systems to produce web pages. In 2019, I decided to unite these…

Examples of some simple regular expressions

*Blog post

Data management

I wanted to use some regular expressions to do a word count for every files on my website. First, I had to remove anything that was not a word. The simplest way is to…

Raynald’s SPSS Tools

*Blog post

Year 2025

Being updated

Data management

SPSS software

Raynald Levesque. Raynald’s SPSS Tools. Available in html format.

Research Integrity and Open Science short course

Blog post

The Department of Continuing Education at Oxford University offers an interesting range of short courses on Evidence-Based Health Care. They had a recent call for feedback…

Definition, Descriptive statistics

*Definitions

Year 2025

Descriptive statistics

Descriptive statistics: Numerical summaries from a sample that characterize that sample without any effort to test a particular hypothesis.

Definition, Normal distribution

*Definitions

Year 2025

Probability concepts

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A free regex book

*Recommendation

Year 2025

String data

This book comes highly recommended by others who know more abour regex (regular expressions) than I do. To my delight, this book is also available for free in pdf format.

Definition, Adverse event

*Definitions

Year 2022

Clinical trials

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Psychological Science

*Recommendation

Datasets

This journal encourages authors to share their data and could be a nice resource for teaching examples.

Data package

*Recommendation

Datasets

Data Package is an effort to standardize descriptions about data that are simple but also able to handle extensions.

regressinator: Simulate and Diagnose (Generalized) Linear Models

*Recommendation

Simulation

An R package that allows you to explore different simulations of generalized linear models.

Score Network

*Recommendation

Datasets

The Score Network is a joint effort spread across several Universities to present interesting and well-documented datasets that can be used for sports analytics.

tidytuesday project

*Recommendation

Datasets

Every Tuesday, this site releases an interesting dataset and encourages interesting analyses. More information is available [here][ref-harmon-nodate-1].

MIMIC-III Clinical Database Demo

*Recommendation

Year 2025

Datasets

SQL

The MIMIC-III database is a massive database of health care records for over 40,000 patients at Beth Israel Deaconess Medical Center from 2001 to 2012. The information is…

Curve fitting - xkcd

*Recommendation

Linear regression

This is an introduction that I wrote for a webinar. Let me share it here. I started with a cartoon from the xkcd site of Scott Munro. Scott Munro produces comics that poke…

Working with invalid names in R

*Blog post

R software

The R programming language has a few rules about names that you can assign for various objects. This can cause some issues with data frames and tibbles that you might be…

Resources for software engineering

*Blog post

Year 2025

Software engineering

I attended a great webinar by Alex Reinhart, From Code to Products - Software Engineering for Data Science. He is part of the Delphi Group at Carnegie Mellon University, a…

Tidyverse style guide

*Recommendation

Year 2025

R software

A style guide is a list of standards that you should follow to make your R code consistent and readable. The tidyverse style guide is one example and most of the…

Multidimensional Deprivation Index

*Recommendation

Year 2025

Datasets

The Census Bureau has an “unofficial” product called the Multidimensional Deprivation Index (MDI), which is described in numerous working papers. This measure is only…

Cleaning height and weight measurements

*Recommendation

Year 2025

R software

The R package growthcleanr will review longitudinal data (including data unevenly spaced over time) on heights and weights for children to find individual observations that…

Qualitative Research. The “What,” “Why,” “Who,” and “How”!

*Recommendation

Year 2025

Qualitative research

This is a very nice “how to” description of qualitative research.

Geocomputation with R

*Recommendation

Year 2025

R software

I was browsing through Chapter 6 of the [ggplot2 book][wickham-2025] by Hadley Wickham, Danielle Navarro, and Thomas Lin Pedersen, which is itself interesting reading. It…

Choices with the group_by and summarize functions

*Blog post

Year 2025

Data management

R software

Uses R code

You have an interesting choice in an R program When you use the group_by function with two or more arguments and follow that with the summarize function. Here is a practical…

Functions to make plain R output look nicer

*Blog post

Year 2025

R software

Uses R code

Most of the statistical summary functions in R produce plain vanilla output. That’s actually good because it allows you to customize things the way you like. I have been…

Image of messy filing system

*Recommendation

Year 2025

Software engineering

This image, available under a Creative Common attribution license, illustrates a chaotic filing system. This will help bring home the point that if you set up a directory…

Engaging People Most Affected by the Problem

*Recommendation

Year 2025

Human side of statistics

This is a nice description with real-world examples of how to involve the community in the planning and execution of your research.

How to make beautiful tables in R

*Recommendation

Year 2024

R software

The basic tables you get when simply printing data and or analysis results are okay, but not publication quality. There are several nice packages in R that can produce…

Whitespace character

*Recommendation

Year 2024

String data

I have often struggled with processing text data in R that has the non-breaking space character (ASCII 160). It turns out that there are about a dozen other characters that…

StatsUpAI Datasets

*Recommendation

Year 2024

Datasets

This is a curated repository of various dataset repositories in elctronic health records, genomics, imaging, microbiome, clinical trials, transcriptomics, and proteomics.

CORGIS: The Collection of Really Great, Interesting, Situated Datasets

*Recommendation

Year 2024

Datasets

Some rather eclectic (and interesting) datasets. All data are stored in a consistent comma-delimited format with very good descriptions of the individual variables.

Using SQL instead of R

*Blog post

Year 2024

SQL

R software

The December 12, 2024 digest of the R help mailing list (Vol 262, Issue 9) had an interesting question. Let me try to paraphrase things here. A researcher had just started…

Survival analysis sample size calculation

*Blog post

Year 2024

Sample size justification

Survival analysis

Uses R code

Someone asked about getting a sample size for a survival analysis project. Here is the scenario. This is a two group comparison. The control group is expected to see 75%…

Data Science Dojo datasets

*Recommendation

Year 2024

Datasets

Data Science Dojo is a company that provides training classes in (you guessed it!) data science. They have stored a nice collection of datasets for learning data science…

A collection of Python tools to help with pregnancy research

*Recommendation

Year 2024

Python programming

A graduate student in our department wrote a nice package to extract information about pregnancy outcomes from electronic health records databases.

Comic take on error bars

*Recommendation

Year 2024

Graphical display

This comic strip by Scott Munro pokes fun at how error bars are perceived by some as imparting profound knowledge. Scott Munro publishes his comics under a Creative Commons…

Enthusiasm at the start…

*Quotation

Year 2024

Human side of statistics

An earlier version of this page was published on new.pmean.com.

Resources for presenting research

*Recommendation

Year 2024

Presenting research

Here are a few articles that I am recommending during my talk on research presentations.

Data masking in R

*Recommendation

Year 2024

R software

One major innovation of tidyverse is the use of non-standard evaluation. It allows you to avoid a lot of repetition of dataframe names in R code. I wrote a page about…

Understanding the Odds Ratio and the Relative Risk

*Recommendation

Year 2024

Measuring benefit and risk

There is a lot of controversy over the use of the odds ratio versus the relative risk. I wrote a brief article on this and explained settings where you should use the odds…

From R Markdown to Quarto

*Recommendation

Year 2024

R software

I attended a short course, From R Markdown to Quarto, which provided a nice introduction to Quarto, a system for producing documents in a wide range of formats that…

closeread

*Recommendation

Year 2024

R software

You can create an interactive document that changes as you scroll through it, highlighting certain features in text of images using the closeread app, an extension for Quarto.

Cleveland Clinic Statistical Dataset Repository

*Recommendation

Year 2024

Datasets

An article in the Journal of Statistics Education describes the development of a repository for real-world datasets associated with actual peer-reviewed publications. You…

String Encoding and R

*Recommendation

Year 2024

R software

![Figure 1. Excerpt from blog post](http://www.pmean.com/new-images/24/string-encoding-01.png{width=80%}

A 50 word biography

*Blog post

Year 2024

Porfessional details

I was asked to write a biography for a short newsletter article that I sent in. The only trick was that it had to be 50 words. Here’s what I wrote (actually 52 words).

Tracking variable modifications in SAS

*Blog post

Year 2024

Data management

SAS software

A student in my Introduction to SAS class posed an interesting question: after you transform some of your variables, how do you keep track of what the original variable is…

Linegraph options in SAS

*Blog post

Year 2024

SAS software

Several of my students wanted information on how to modify graphs in SAS. I’m glad they asked, because the worst thing you can do with any software is to take the graph that…

Scatterplot options in SAS

*Blog post

Year 2024

SAS software

Several of my students wanted information on how to modify graphs in SAS. I’m glad they asked, because the worst thing you can do with any software is to take the graph that…

Histogram options in SAS

*Blog post

Year 2024

SAS software

Several of my students wanted information on how to modify graphs in SAS. I’m glad they asked, because the worst thing you can do with any software is to take the graph that…

What happens when you leave out a semicolon in SAS?

*Blog post

Year 2024

SAS software

SAS uses semicolons at the end of each statement. This allows you to stretch a long program statement across two or more lines. I want to show what happens when you forget a…

A gentle introduction to SHAP values in R

*Recommendation

Year 2024

Interpretable machine learning

SHAP values provide you a way to interpret the impact of individual independent variables in a variety of “black box” machine learning models, such as Random Forest. It…

Effect sizes in linear regression and analysis of variance

*Blog post

Analysis of variance

Linear regression

I have been asked to produce effect size measures for a linear regression model. I do not like effect size measures but people who are a lot smarter than me do ask for them…

ggtern: Ternary Diagrams Using ggplot2

*Recommendation

Year 2024

Graphical display

Ternary plots display three proportions which must sum to 1. It uses a triangular plotting area where each corner of the triangle represents an extreme with a single…

AI and the Meaning of Life

*Recommendation

Year 2024

Artificial intelligence

The Existential Comics website, written by Corey Mohler, is an exploration of major ideas in Philosophy that places famous Philosophers of the past in modern contexts to an…

Nice layout for comparison of categorical outcomes

*Blog post

Year 2024

Incomplete page

R software

Uses R code

While it is easy to get R to produce descriptive statistics for categorical outcomes in a research study, it is a bit harder to get R to produce a layout that is…

Writing the discussion section of a research publication

*Blog post

Year 2024

Writing research papers

I am bringing together resources for various chapters in my book proposal. One of the chapters (chapter 15 in one proposed outline and section 3.7 a different outline) is on…

Infovis and Statistical Graphics: Different Goals, Different Looks

*Recommendation

Year 2024

Being updated

The authors draw a distinction between Information Visualization (infovis) and Statistical Graphics. The goals of Infovis experts are to grab attention and tell a story. The…

An epidemic of scientific fakery threatens to overwhelm publishers

*Recommendation

Year 2024

Fraud in research

The number of retracted papers has grown rapidly over the past year. Marcus and Oransky, creators of the Retraction Watch website, explain why this is happening and offer…

Different end times in survival data

*Blog post

Year 2024

Ask Professor Mean

Survival analysis

Uses R code

Dear Professor Mean, I am running a survival analysis with two groups and one group was followed for 190 days and the other for 225 days. Would that cause any bias?

R datasets

*Recommendation

Year 2024

Datasets

R software

Both base R and many of the R packages have datasets included which help illustrate the use of various features in R. This site consolidates all of those datasets in a…

Illustrating splines using the diamond pricing dataset

*Blog post

Year 2024

Nonlinear regression

R software

Splines provide a useful way to model relationships that are more complex than a simple linear relationship. They work in a variety of regression models. Here is an…

Illustrating the lasso model using the Worcester Heart Attack Study

*Blog post

Year 2024

Survival analysis

R software

Uses R code

The lasso model allows you to effectively identify important features in a large regression model. Here is an illustration of how to use a the lasso model with survival data…

Illustrating splines using the Worcester Heart Attack Study

*Blog post

Year 2024

Incomplete page

Survival analysis

R software

Uses R code

Splines provide a useful way to model relationships that are more complex than a simple linear relationship. They work in a variety of regression models. Here is an…

Illustrating imputation of missing data using the Titanic dataset

*Blog post

Year 2024

Missing data

R software

Uses R code

Multiple imputation is a way to properly account for missing values without causing bias. Simpler forms of imputation, such as replacing missing values with the mean of the…

Illustrating splines using the Titanic dataset

*Blog post

Year 2024

Nonlinear regression

R software

Uses R code

Splines provide a useful way to model relationships that are more complex than a simple linear relationship. They work in a variety of regression models. Here is an…

A tricky program to debug

*Blog post

Year 2024

R software

I’ve had a couple of students bring me R programs that did not work. Looking at the output, I could not figure out why they did not work. It turns out that you have to look…

Center for Advancement and Dissemination of Intervention Optimization

*Recommendation

Year 2024

Research design

Many behavioral interventions include several discrete components. You should consider trying to optimize the mix of these components. Intervention Optimization provides a…

Mendeley data

*Recommendation

Year 2024

Datasets

While there are several websites that offer repositories for datasets associated with peer-reviewed publications, this one seems to offer a better set of choices: full and…

JBI Manual for Evidence Synthesis

*Recommendation

Year 2024

Systematic overviews

A nice overview of a broad range of systematic overviews for qualitative evidence, evidence of effectiveness, textual evidence, economic evidence, and scoping reviews.

R Inferno

*Recommendation

Year 2024

R software

Warning! This document is not for those who are fairly new to R. I don’t want you to get scared away!

Biography for 2024 talk

*Blog post

Year 2024

Personal details

I’m tentatively scheduled to give a webinar for the Consulting Section of the American Statistical Association on May 2. They wanted a short biography of me that they could…

Encoding example in R

*Blog post

Year 2024

Data management

Alphabets other than English require special characters. Computers have evolved many different ways to handle these special characters.

Finding customers webinar

*Blog post

Year 2024

Human side of statistics

I am tentatively giving a webinar for the Consulting Section of the American Statistical Association on May 2. Here is the title and abstract.

Security policies at my job

*Blog post

Year 2024

Being updated

There are several important security policies at my job that are worth noting here. They provide good general guidance for anyone working with sensitive data.

“Final”.doc

*Recommendation

Year 2024

Software engineering

PhD Comics is satirical look at life as a graduate student. This particular comic resonated with me, so I am sharing it here. Although this comic strip is not directly about…

HCL-Based Color Palettes

*Recommendation

Year 2024

Being updated

A review of spline function procedures

*Recommendation

Year 2024

Linear regression

A very nice and not too technical overview of the various spline models and the libraries in R that implement them.

The Art of LaTeX

*Recommendation

Year 2024

Writing research papers

I use LaTeX to create mathematical formulas and it does a great job at it. There are so many features, however, that could make my formulas look even nicer. This detailed…

Distribution-free Bayesian Analysis

*Recommendation

Year 2024

Bayesian statistics

The commonly used examples of Bayesian data analysis will require specific distributional assumptions. These can be relaxed somewhat. But it is possible to provide a…

The parsimony principle…

*Quotation

Year 2024

Modeling issues

An earlier version of this page was published on new.pmean.com.

With four parameters…

*Quotation

Year 2024

Being updated

An earlier version of this page was published on new.pmean.com.

Suggestions for topics on a methodology paper

*Blog post

Year 2023

Research methodology

A colleague of mine is guest editor for journal that is preparing special issue on research methodology. He wanted to know if I was interested in contributing a paer, and of…

Finding good research examples

*Blog post

Year 2023

Information searching

You find yourself using what, to you, is a new statistical approach, multiple imputation, and you’re uncertain about how to approach it. You’re not sure what options you…

The best reasons to run a pilot study

*Blog post

Year 2023

Pilot studies

There’s a common saying among pediatricians: children are not little adults. You can’t take a drug therapy that works in adults and scale it down to a kid-sized treatment.…

What is a partial correlation?

*Blog post

Year 2023

Correlation

Uses R code

The concept of controlling for a third variable is an important one to understand in Statistics. When you are looking at data without the benefit of randomization, sometimes…

Arrow R Package

*Recommendation

Year 2023

R software

Apache Arrow is a system for storing columnar data that is fast and can handle very large files. I have not had a chance to work with this format, but it looks very…

Joining Posit’s Polyglot Data Science Mission

*Recommendation

Year 2023

Python programming

Wes McKinney describes much of his early work with open source software and his recent decision to join Posit.

Standardized survival functions

*Recommendation

Year 2023

Being updated

Getting a survival function that is properly adjusted for covariates is tricky. This webpage documents how you could do this using a Stata macro, stmp_standsurv.

Documenting a sample size justification

*Blog post

Year 2023

Sample size justification

If you provide justification for a proposed sample size, you should include enough information to allow others to reproduce your calculations. Here is a brief overview of…

ggplot2: Elegant Graphics for Data Analysis (3e)

*Recommendation

Year 2023

Graphical display

Online version of the third edition of a book by the developers of ggplot2. It is described (as of November 2023) as a “work-in-progress”.

The Not So Short Introduction to LaTeX

*Recommendation

Year 2023

Writing research papers

LaTex provides a great environment for publishing mathematical documents. Chapter 3 of this guide, which shows how to write publication ready mathematical formulas, is…

McNemar’s test

*Blog post

Year 2023

Measuring benefit and risk

Uses R code

I mentioned McNemar’s test in a short article for my Monthly Mean newsletter. Here are more details about this test.

Illustration of the rule of 16

*Blog post

Year 2023

Sample size justification

The rule of 16 is a convenient rule to give quick estimate of the sample size that you might need in a study. It states that if you want to conduct a study with enough power…

Using R to automate file uploads

*Blog post

Year 2023

R software

I am trying to automate some tasks that will streamline my workload. One of those tasks is uploading files to my website. I am just starting to explore how this can be done.…

UM system resources for generative AI

*Blog post

Year 2023

Artificial intelligence

I attended a webinar sponsored by Missouri Online on the use of generative AI in education. The author referred to two resources that they provide.

Key data privacy references

*Blog post

Year 2023

Privacy in research

I attended a webinar on data privacy and the speakers opened with a series of seminal articles about how easy it is to re-identify data that you might have thought was…

Too many colors spoil the graph

*Blog post

Year 2023

Being updated

Uses R code

When you draw a graph, either a bar chart, a scatterplot, or even a pie chart, you have the choice of a broad range of colors that you can use. R, for example, has 657…

Information for a new research grant

*Blog post

Year 2023

Professional details

I may be working with a consulting group, Mountain Whisper Light, on a grant proposal to be sent to the Department of Natural Resources in the state of Washington. I don’t…

Using a linear Taylor series approximation to estimate rounding error

*Blog post

Year 2023

Mathematics

Uses R code

When I run, I have an app that announces the distance traveled (in kilometers) at the end of every minute. But since the app rounds to one decimal place, there is a bit of…

Introduction to Data Technologies

*Recommendation

Year 2023

Data management

R software

SQL software

An interesting book, published under an open source license and available in html or pdf versions. It is a rather eclectic mix of html, css, SQL, and R. The guiding theme is…

Displaying SPSS syntax commands

*Blog post

Year 2023

SPSS software

In SPSS, you can do all of your data manipulations and data analysis using the menus and dialog boxes. You also could use program code, which SPSS calls “syntax”. Most SPSS…

A few details about myself

*Blog post

Year 2023

Professional details

I was asked to provide a few details about myself (a bio blurb) to be used at the first graduate research seminar for Fall semester 2023.

How scientists work to correct the record when there is an error in a paper

*Recommendation

Year 2023

Ethics in research

A recent scandal involving the former president of Stanford, Marc Tessier-Lavigne, offers an opportunity to see how the research enterprise works to correct errors. To be…

Modern Data Science with R

*Recommendation

Year 2023

Teaching resources

A very complete book available for free online.

Reshaping longitudinal data in SAS

*Blog post

Year 2023

SAS software

If you work with longitudinal data, you may see the data arranged in a tall and thin format or in a short and fat format. The tall and thin format is useful for some data…

Primer on Python for R Users

*Recommendation

Year 2023

Python programming

Some of the topics are a bit abstract, but in general, a quite nice description of how Python differs from R.

Feature Engineering and Selection: A Practical Approach for Predictive Models

*Recommendation

Year 2023

Data mining

This book can be bought, but is also available for free in html format. Here is a brief description taken from the Amazon page for this book. “The process of developing…

Swarm plot examples

*Blog post

Year 2023

Graphical display

I came across a new type of plot yesterday, a swarm plot. It looks like an interesting alternative to jittering. You can create these graphs using the seaborn library of…

Pediatric Pandemic Network

*Recommendation

Year 2023

Children in research

A colleague of mine mentioned this research consortium of children’s hospitals, including Children’s Mercy. They fund a variety of research projects and I might work with…

Another pitch for my graphic novel project

*Blog post

Year 2023

Ethics in research

I sent out an email recently about a project I have been thinking about doing for quite a few years. Here is the general text of the email with a few changes to avoid…

Transforming healthcare research with technology’s latest capabilities

*Recommendation

Year 2023

Important statisticians

Well, I filed this under the tage “Important statisticians” but this interview for the Oracle Research in Action podcast with Mark Hoffman is stretching that tag a bit. Mark…

SAS Webinars

*Recommendation

Year 2023

SAS software

SAS Institute offers a variety of live and recorded webinars that highlight important issues in Statistics and how products from SAS Institute can help with them.…

Florence Nightingale’s legacy lives on

*Recommendation

Year 2023

Important statisticians

A nice summary of the importance of Statistics and Evidence-Based Health Care to the work of Florence Nightingale.

Version control basics, updating a local project using git

*Blog post

Year 2023

Software engineering

This is part of series of articles on how to set up and use version control on your computer. There are many systems for version control. In these articles, you will use a…

Version control basics, creating a personal repository

*Blog post

Year 2023

Software engineering

This page has been replaced with two other pages, git-local-installation and git-local-updates. I also hope to add a few more pages about ths in the future.

Version control basics, installing a local version of git

*Blog post

Year 2023

Software engineering

This is part of series of articles on how to set up and use version control on your computer. There are many systems for version control. In these articles, you will use a…

Version control basics, updating a local project using git

*Blog post

Year 2023

Incomplete page

Software engineering

This page has been replaced with two other pages, git-local-installation and git-local-updates. I also hope to add a few more pages about ths in the future.

How can I estimate relative risk using GLM for common outcomes in cohort studies

*Recommendation

Year 2023

Measuring benefit and risk

It is easy to get odds ratios from logistic regression, but what do you do when you want to estimate relative risks instead. There are several possible solutions, and this…

Resources mentioned during SDSS

*Blog post

Year 2023

Teaching resources

I want to list some of the resources mentioned at various talks during SDSS 2023.

NLM Grants for Scholarly Works in Biomedicine and Health

*Blog post

Year 2023

Writing research grants

The National Library of Medicine just released a Notice of Funding Opportunity, NLM Grants for Scholarly Works in Biomedicine and Health, PAR-23-183. This is to help prepare…

Overview of Randomization Tests

*Recommendation

Year 2023

Statistical computing

This is a detailed overview of randomization tests. It starts with the general philosophy behind randomization tests. Then it provides concrete examples in a variety of…

Re-Reading Deming’s 14 Points in the Era of Data Science

*Recommendation

Year 2023

Data science

Quality improvement

An interesting attempt to adapt Deming’s Fourteen Points, written over 40 years ago, to modern data science.

Statistical Literacy: A Study of Confounding

*Recommendation

Year 2023

Risk adjustment

THe author reviews many articles on statistical literacy and notes some interesting trends in how frequently the term “confounding” appears in those articles. He then offers…

Starting to think about AI Fairness

*Recommendation

Year 2023

Data science

Some algorithms in Artificial Intelligence (AI) have been shown to cause harm to already disadvantaged groups. Fixing this is not easy. In particular, deciding when an…

Non-standard evaluation inside functions and loops

*Blog post

Year 2023

R software

Uses R code

One of the big changes that the tidyverse made to the R programming language is the use of non-standard evaluation (NSE). This is sometimes described more explicitly as tidy…

An Introduction to the Harrell”verse”

*Recommendation

Year 2023

Linear regression

Frank Harrell has packed in some pretty nice features in his Hmisc and rms packages. This post outlines some of these using practical examples.

Magrittr aliases

*Recommendation

Year 2023

R software

When you are using pipes in R, sometimes you need access to a function that doesn’t look like a function, such as the function to set names for a data frame. The programmers…

A mixture of normal distributions

*Blog post

Year 2023

Statistical theory

There is a simple theoretical result involving a mixture of normal distributions. If you select a normal distribution with a mean of zero and let the precision of that…

The hedging hyperprior for the normal distribution: unknown mean, unknown precision

*Blog post

Year 2023

Bayesian statistics

Uses R code

I want to write a paper about the hedging hyperprior. I need to work out some simple examples first. Here is an example involving the normal distribution.

The hedging hyperprior for the normal distribution: known mean, unknown precision

*Blog post

Year 2023

Bayesian statistics

Uses R code

I want to write a paper about the hedging hyperprior. I need to work out some simple examples first. Here is an example involving the normal distribution.

The modified power prior

*Blog post

Year 2023

Bayesian statistics

Incomplete page

Uses R code

I want to write a paper about the hedging hyperprior. Here is a brief description of an approach it is comparable to, the modified power prior.

A thank you from BMJ Open

*Blog post

Year 2023

Professional details

I don’t do my fair share of peer-reviews, but I did do one recently and got a nice thank you note on Valentine’s Day. I am reproducing the text here, so I can refer to it…

The hedging hyperprior for the exponential distribution

*Blog post

Year 2023

Bayesian statistics

Uses R code

I want to write a paper about the hedging hyperprior. I need to work out some simple examples first. Here is an example involving the exponential distribution.

The hedging hyperprior for the normal distribution: unknown mean, known precision

*Blog post

Year 2023

Bayesian statistics

Uses R code

I want to write a paper about the hedging hyperprior. I need to work out some simple examples first. Here is an example involving the normal distribution.

The Imminent Danger of A.I. Is One We’re Not Talking About

*Recommendation

Year 2023

Data science

While there have been recent discussions about Chat GPT and other Artificial Intelligence systems behaving badly, this author cites more important questions: Who will…

Using work resources on outside consulting

*Blog post

Year 2023

Human side of statistics

Dear Professor Mean, I am looking at a post-retirement business venture as a solo statistical consultant. I would wind down the hours at my current job while I build up my…

Early pages on micro-arrays

*Blog post

Year 2023

Genomic analysis

Back around 1998 through about 2004, I tried my best to understand how to manage data from a micro-array experiment and how to analyze it properly. I started some web pages…

Confirmation bias as a misfire of normal Bayesian reasoning

*Recommendation

Year 2023

Bayesian statistics

Critical appraisal

A brief, but interesting argument that confirmation bias is just an example of applying an informative prior. This is an argument that has been made before and one that I…

Beware the man of one study

*Recommendation

Year 2023

Systematic overviews

This blog post starts with a quote from Thomas Aquinas, “Beware the man of one book” and updates it to arguments relying on peer-reviewed studies. He spends a fair amount of…

A critique of data sharing practices

*Blog post

Year 2023

Teaching resources

I attended a panel discussion on data sharing practices in peer-reviewed articles. The major focus was on papers that stated “Data available upon request.” This statement is…

Special issue on teaching reproducibility

*Recommendation

Year 2023

Teaching resources

The Journal of Statistics and Data Science Education has a special issue on teaching reproducibility. I haven’t read the whole issue, but the articles I have read are…

Essential Statistics with R and Python

*Recommendation

Year 2023

Teaching resources

This book has two advantages. First, it is freely downloadable. Second, it uses both R and Python code to solve the problems. The book covers most of the basic statistics…

Download statistics of R packages

*Recommendation

Year 2023

R software

Both CRAN and Bioconductor track the number of downloads for their packages over time. You can access these statistics for any of the packages you are interested in. A large…

Writing a scope of work

*Recommendation

Year 2023

R software

I attended a great panel discussion at the Conference on Statistical Practice on how to write a scope of work. Most of the panelists cited Peterson et al 2022 in their…

My boxplot shows a box but no whiskers

*Blog post

Year 2022

Graphical display

One of my favorite graphs is the box plot. It is a visualization of a five number summary. Those five numbers are minimum, 25th percentile, median (aka the 50th percentile)…

Troubleshooting tips when you have errors in your SAS code

*Blog post

Year 2022

SAS software

One of my SAS students wanted advice about how to troubleshoot. It’s not an easy question to answer and depends a lot on the type of problem you encounter. Here are a few…

Naming your consulting company

*Blog post

Year 2022

Human side of statistics

Someone asked about what to name their new statistical consulting company. They were worried about choosing a name that was too similar to another company out there. This…

What it means when your variable names are numbers

*Blog post

Year 2022

SAS software

More than one of my students had trouble importing a text file and ended up with numbers as variable names. Here’s what went wrong.

Statement order in SAS programs

*Blog post

Year 2022

SAS software

Someone asked about deciding how to know what order to put SAS programming statements in. I answered that you just need to use a bit of common sense.

Modern books on mathematical statistics

*Blog post

Year 2022

Teaching resources

Someone asked for some recommendations for books on mathematical statistics that take a more modern and applied approach. I am not at all familiar with this, so I…

D3, Data-Driven Documents

*Recommendation

Year 2022

Graphical display

D3 is a powerful system for visualization with a small footprint. This page gives an overview of D3 and some very basic tutorials.

Schoenfeld residuals

*Blog post

Year 2022

Rmarkdown code

Survival analysis

There are several different types of residuals in a Cox proportional hazards model. One of them is the Schoenfeld residuals. They are used to test the proportional hazards…

And finally I would like to thank my cat

*Quotation

Year 2022

Writing research papers

Last Friday’s footnote about unusual dissertation acknowledgments prompted some of you to share others, and I noticed a theme: Pets! Hillary Anger Elfenbein, a business…

Machine learning resources from a seminar by Shuhao Cao

*Blog post

Year 2022

Data science

I attended an interesting seminar presented by Shuhao Cao, a new faculty member in Mathematics and Statistics at UMKC. Almost all of the talk was over my head, but I did…

The POSIX time standard

*Blog post

Year 2022

Data science

Rmarkdown code

I thought I understood everything about how computers represent time, but apparently not. There is an important time standard, POSIX time, that I was not all that aware of.…

Using regular expressions in SAS

*Recommendation

Year 2022

SAS software

Regular expressions are a powerful way to identify and manipulate string data. SAS implements regular expressions through through the prxparse, prxmatch, prxsubstr, prxposn…

Blogdown equations

*Blog post

Year 2022

Data management

I write my updated blog using a mix of Markdown (*.md) and R Markdown (*.Rmd) files. If the blog post has R code in it, I use R Markdown. But I am finding that equations can…

Confusion caused by multiple date formats

*Blog post

Year 2022

Data management

If you are given data that includes dates, expect confusion. Dates can be represented in many different ways.

Internal storage format for dates

*Blog post

Year 2022

Data management

If you are given data that includes dates, expect confusion. Dates can be represented in many different ways.

Missing value functions

*Blog post

Year 2022

Data management

Comparisons involving missing values are tricky.

Missing value hell

*Blog post

Year 2022

Data management

There’s no mincing words here. Missing values are hell for every statistician. Here are a few examples.

Why weighting for iid data is inefficient

*Blog post

Year 2022

Statistical theory

Usually, you use weighting to gain efficiency in a setting where different data points have different variances. But if the variances are equal, such as in an independent…

Recommendation for the oral presentation at a thesis defense

*Blog post

Year 2022

Human side of statistics

I got a question about what to prepare for the presentation that a student was going to do for a thesis defense.

How can cloud computing help improve equity in the classroom and data science research

*Blog post

Year 2022

Software engineering

I attended a webinar presented by Dartmouth University, the ninth in a series of talks in the Summer 2022 Data Science and AI Webinar Series. The speaker, Mohammad…

OpenIntro datasets

*Recommendation

Year 2022

Datasets

OpenIntro is a site that publishes several open source textbooks. This page on their site provides a compilation of datasets from a variety of sources that can be used with…

Recommendations for qualitative research in five categories

*Recommendation

Year 2022

SAS software

Software engineering

The first in a series of tweets that lists a few resources for five (nine?) areas of qualitative research. These areas are: case study, ethnography, coding, interviewing…

List of datasets for machine-learning research

*Recommendation

Year 2022

Datasets

A list of hundreds of datasets: some are numeric, some are labelled images or sounds, that can be used to test various machine learning algorithms.

Different parameterizations for one factor ANOVA

*Blog post

Year 2022

Analysis of variance

Rmarkdown code

I’m trying to understand some of the basics of contrasts in analysis of variance. In particular, I want to figure out some alternative parameterizations of the coefficients…

A simple visual alternative to all pairwise comparisons

*Blog post

Year 2022

Analysis of means

Rmarkdown graphs

The classic follow-up to a significant F test in analysis of variance is examining all pairwise differences in means. It’s great for many problems, but sometimes you may not…

Dunnett’s test

*Blog post

Year 2022

Analysis of means

Rmarkdown graphs

I’m a big fan of Analysis of Variance (ANOVA). I use it all the time. I learn a lot from it. But sometimes it doesn’t test the hypothesis I need.

Scientific American article on the bootstrap

*Recommendation

Year 2022

Statistical computing

The bootstrap is a computational approach that allows you to create confidence intervals and hypothesis tests in a wide range of setting where normality or asymptotic…

Git cartoon from xkcd

*Recommendation

Year 2022

Statistical computing

I use git for version control, but I have to admit that I don’t understand most of its commands. This cartoon satirizes my perspective, which apparently is common among many…

Scientific American article on the bootstrap

*Recommendation

Year 2022

Survival analysis

This is a fairly comprehensive review of the variety of approaches you can use to model recurrent events in a time-to-event model. The authors share some code as well. You…

Interesting links from the UseR 2022 conference

*Blog post

Year 2022

Teaching resources

I am attending the UserR conference this week. It is a virtual format, which has its advantages and disadvantages. I want to track a variety of links that I found from the…

Selecting a Data Repository

*Recommendation

Year 2022

Data sharing

The National Institutes of Health encourages researchers that it funds to share their data, subject to various privacy conditions. If you do share your data, NIH has a lot…

A Taste of Observable

*Recommendation

Year 2022

Graphical display

I was researching quarto, a successor to RMarkdown, and learned that it supports something called Observable. I have a difficult time characterizing Observable. It appears…

With Quarto Coming, is R Markdown Going Away? No.

*Recommendation

Year 2022

R software

I attended a talk where the presenter used quarto rather than RMarkdown to create their slides. I had never heard about quarto, so I did some searching. There are a lot of…

Zoom security options

*Blog post

Year 2022

Teaching resources

I use Zoom for a variety of meetings, webinars, etc. Back in May 2022, I got Zoombombed. Several neo-nazis joined a Zoom meeting I was hosting and raised havoc. With help…

Behind GitHub’s new authentication token formats

*Recommendation

Year 2022

Epidemiology

An article by Gary Taubes in 1995 made a big splash by alleging that Epidemiology has met its limits because the effect sizes that they were looking for in recent years were…

SAS Tutorial | How to use Git with SAS

*Recommendation

Year 2022

SAS software

Software engineering

I attended a very nice talk by Chris Hemedinger about using git with SAS. Git is a program that uses version control to manage a programming project. It is integrated nicely…

Behind GitHub’s new authentication token formats

*Recommendation

Year 2022

Software engineering

I only have a vague idea what an authentication token is, but I should probably learn more. I got a notice from GitHub that I was using an old authentication token and…

Deploy Now

*Recommendation

Year 2022

Website details

I am upgrading and consolidating my website and blog to blogdown, an R package based on Hugo. My website is currently hosted by Ionos (formerly 1-and-1). Ionos is offering a…

Understanding Random Forest

*Recommendation

Year 2022

Website details

This is a nice non-technical explanation of how the Random Forest model works and why it is so effective.

Library Research Tutorials

*Recommendation

Year 2022

Writing research papers

If you plan on writing a serious research paper, you should work closely with a librarian, who can help in a variety of different areas. The librarians at UMKC have prepared…

Testing d3

*Blog post

Year 2022

Graphical display

Incomplete page

I am interested in developing some visualization applications using d3. You can run d3 from within R Markdown.

Definition, Adverse reaction

*Definitions

Year 2022

Clinical trials

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Definition, Alpha

*Definitions

Year 2022

Hypothesis testing

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Definition, Beta

*Definitions

Year 2022

Hypothesis testing

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Definition, Binomial distribution

*Definitions

Year 2022

Probability concepts

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Definition, Binomial mean

*Definitions

Year 2022

Probability concepts

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Definition, Binomial probability

*Definitions

Year 2022

Probability concepts

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Definition, Boxplot

*Definitions

Year 2022

Graphical display

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Definition, Case-control study

*Definitions

Year 2022

Research design

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Definition, Categorical data

*Definitions

Year 2022

Measurement scales

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Definition, Cohort study

*Definitions

Year 2022

Research design

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Definition, Common cause variation

*Definitions

Year 2022

Quality improvement

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Definition, Conditional probability

*Definitions

Year 2022

Probability concepts

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Definition, Continuous data

*Definitions

Year 2022

Measurement scales

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Definition, Control chart

*Definitions

Year 2022

Quality improvement

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Definition, Convenience sample

*Definitions

Year 2022

Research design

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Definition, Correlation coefficient

*Definitions

Year 2022

Descriptive statistics

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Definition, Cross sectional study

*Definitions

Year 2022

Research design

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Definition, Crossover study

*Definitions

Year 2022

Research design

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Definition, Decision rule

*Definitions

Year 2022

Hypothesis testing

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Definition, Dependent variable

*Definitions

Year 2022

Inferential statistics

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Definition, Descriptive study

*Definitions

Year 2022

Research design

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Definition, Diagnostic test

*Definitions

Year 2022

Diagnostic testing

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Definition, Entropy

*Definitions

Year 2022

Probability concepts

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Definition, Experimental design

*Definitions

Year 2022

Research design

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Definition, Fagan nomogram

*Definitions

Year 2022

Diagnostic testing

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Definition, Geometric mean

*Definitions

Year 2022

Descriptive statistics

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Definition, Independence

*Definitions

Year 2022

Probability concepts

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Definition, Independent variable

*Definitions

Year 2022

Inferential statistics

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Definition, Inferential statistics

*Definitions

Year 2022

Hypothesis testing

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Definition, Interquartile range

*Definitions

Year 2022

Descriptive statistics

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Definition, Interval data

*Definitions

Year 2022

Measurement scales

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Definition, Kappa

*Definitions

Year 2022

Descriptive statistics

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Definition, Likelihood ratio

*Definitions

Year 2022

Diagnostic testing

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Definition, Longitudinal study

*Definitions

Year 2022

Research design

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Definition, Mann-Whitney-Wilcoxon test

*Definitions

Year 2022

Hypothesis testing

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Definition, Mean

*Definitions

Year 2022

Descriptive statistics

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Definition, Median

*Definitions

Year 2022

Descriptive statistics

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Definition, Mode

*Definitions

Year 2022

Descriptive statistics

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Definition, Mosaic plot

*Definitions

Year 2022

Graphical display

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Definition, Negative predictive value

*Definitions

Year 2022

Diagnostic testing

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Definition, Nominal data

*Definitions

Year 2022

Measurement scales

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Definition, Observational study

*Definitions

Year 2022

Research design

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Definition, Odds

*Definitions

Year 2022

Probability concepts

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Definition, Odds ratio

*Definitions

Year 2022

Probability concepts

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Definition, Ordinal data

*Definitions

Year 2022

Measurement scales

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Definition, Parallel groups study

*Definitions

Year 2022

Research design

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Definition, Parameter

*Definitions

Year 2022

Hypothesis testing

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Definition, Percentiles

*Definitions

Year 2022

Descriptive statistics

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Definition, Phi coefficient

*Definitions

Year 2022

Descriptive statistics

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Definition, Binomial probability

*Definitions

Year 2022

Descriptive statistics

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Definition, Poisson distribution

*Definitions

Year 2022

Probability concepts

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Definition, Population

*Definitions

Year 2022

Hypothesis testing

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Definition, Positive predictive value

*Definitions

Year 2022

Diagnostic testing

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Definition, Purposive sample

*Definitions

Year 2022

Research design

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Definition, P-value

*Definitions

Year 2022

Hypothesis testing

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Definition, Qualitative study

*Definitions

Year 2022

Research design

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Definition, Quota sample

*Definitions

Year 2022

Research design

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Definition, Random sample

*Definitions

Year 2022

Research design

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Definition, Range

*Definitions

Year 2022

Descriptive statistics

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Definition, Ratio data

*Definitions

Year 2022

Measurement scales

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Definition, Retrospective study

*Definitions

Year 2022

Research design

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Definition, Sample

*Definitions

Year 2022

Hypothesis testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Definition, Sensitivity

*Definitions

Year 2022

Diagnostic testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Definition, Special cause variation

*Definitions

Year 2022

Quality improvement

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Definition, Specificity

*Definitions

Year 2022

Diagnostic testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Definition, Standard deviation

*Definitions

Year 2022

Descriptive statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Definition, Standard error

*Definitions

Year 2022

Descriptive statistics

Hypothesis testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Definition, Statistic

*Definitions

Year 2022

Hypothesis testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Definition, Stem and leaf diagram

*Definitions

Year 2022

Graphical display

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Definition, t-statistic

*Definitions

Year 2022

Hypothesis testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Definition, Type I error

*Definitions

Year 2022

Hypothesis testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Definition, Type II error

*Definitions

Year 2022

Hypothesis testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Definition, Weighted mean

*Definitions

Year 2022

Descriptive statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

My writing goals for Summer 2022

*Blog post

Year 2022

Website details

I did not make much progress on updating my website over the past few months. My teaching load was heavier than what I was used to, and I had other writing goals for various…

Improving Representation in Clinical Trials and Research

*Recommendation

Year 2022

Health disparities

This report summarizes the work of a task on diverse representation in clinical research. It summarizes the problems with under-representation of minorities in clinical…

Getting started with SAS On Demand for Academics

*Blog post

Year 2022

SAS software

Teaching a class in SAS is tricky because some students do not have easy access to the SAS software. SAS is a commercial product and the price that you would have to pay is…

IPUMS Health Surveys

*Recommendation

Year 2022

Data science

IPUMS is a project that stores and harmonizes data from various public sources. This particular site harmonizes data from the National Health Interview Survey and the…

Using ML for complex survey data

*Recommendation

Year 2022

Data science

Complex surveys

Preparing raw clinical data for publication

*Recommendation

Year 2022

Data sharing

Here are some practical suggestions on how to prepare the raw data for inclusion in a peer-reviewed article. The emphasis is on protecting patient confidentiality.

Whose data set is it anyway?

*Recommendation

Year 2022

Data sharing

Andrew Vickers makes a strong case for the need to share research data for any peer-reviewed publication.

Using the foreach package

*Recommendation

Year 2022

R software

The foreach package provides an easy way to take advantage of parallel processing within an R program. This vignette shows how to do this with some simple examples.

An international multi-centre cohort study of weight loss in overweight cats

*Recommendation

Broken-image-link

Year 2022

Teaching resources

One of my students used an interesting dataset for their final project. It is freely available on the web and might be one I would use in future classes.

Creative Commons

*Recommendation

Year 2022

Open source

The most commonly used open source licenses for journal articles are those developed by a volunteer organization, Creative Commons. They provide options that can insure that…

What Influences Saturation? Estimating Sample Sizes in Focus Group Research

*Recommendation

Year 2022

Qualitative research

Sample size justification

One of my students shared this paper with me. It talks about when you should expect to see saturation in a focus group study. It uses some hard date to answer this question.

Open Source Initiative, Licenses and Standards

*Recommendation

Year 2022

Open source

There are a variety of open source licenses that are used for software. This site lists some of the most popular licenses and answers some common questions.

What Influences Saturation? Estimating Sample Sizes in Focus Group Research

*Recommendation

Year 2022

Qualitative research

Sample size justification

One of my students shared this paper with me. It talks about when you should expect to see saturation in a focus group study. It uses some hard date to answer this question.

The Use and Interpretation of Competing Risks Regression Models

*Recommendation

Year 2022

Data science

This is a nice overview of competing risks that draws important distinctions from the Cox proportional hazards model.

Interesting resources discovered during IDAD 2022

*Blog post

Year 2022

Teaching resources

During the talks at the Innovations in Design Analysis and Dissemination (IDAD): Frontiers in Biostatistics & Data Science in 2022, I took a peek at various website and…

Different creatures in the R zoo

*Blog post

Year 2022

R software

Rmarkdown code

R has a variety of ways of storing information. It is a hodge-podge of different things. I’ll call these “things” creatures, though that is probably not the right word. Let…

Interesting resources discovered during Nexus Informatics 2022

*Blog post

Year 2022

Informatics

During the talks at the Nexus Informatics conference of 2022, I took a peek at various website and articles. These were either ones that the speakers mentioned or ones I…

A quick overview of various git verbs

*Blog post

Year 2022

Software engineering

I am a beginner in using version control, even though I have relied on it for several years now. I’m beginning to encourage others to use version control with joint projects…

IBM Watson: Why Is Healthcare AI So Tough?

*Recommendation

Year 2022

Data science

IBM Watson is a supercomputer that has handled some difficult problems that are diffuse and poorly defined. In particular, it was able to compete in a general knowledge…

There’s a Smarter Way to Think About the Under-5 Vaccine.

*Recommendation

Year 2022

Bayesian statistics

A statistician and parent of three young children laments a recent delay in approval of a COVID vaccine for children under the age of 5. He argues that the FDA emphasis on…

Confusion about observational designs

*Blog post

Year 2022

Observational studies

In one of my lectures on Clinical Research Methodology, I point out how easy it is to confuse various types of observational studies for one another. This is usually because…

Scientific writing, Strategies and tools for students and advisors

*Recommendation

Year 2022

Writing research papers

A guide from the beginning to the end of writing a scientific paper.

A Reviewer’s Quick Guide to Assessing Open Datasets

*Recommendation

Year 2022

Open data

A brief guide for peer reviewers who have to look at the datasets being shared as part of a proposed publication.

The ASCCR Frame for Learning Essential Collaboration Skills

*Blog post

Year 2022

Human side of statistics

Incomplete page

Consulting on statistical issues with a non-statistician is an art. Eric Vance and Heather Smith outline an effective process described by an acronym ASCCR (Attitude…

Using change scores

*Blog post

Year 2022

Risk adjustment

Incomplete page

On the ASA Connect Digest, someone was asking about references discussing the practice of using change scores as the outcome variable with the baseline variable as a…

How Big of a Sample Size do you need for Factor Analysis

*Recommendation

Year 2022

Sample size justification

Determining an appropriate sample size for Factor Analysis is tricky. You can’t easily use a power calculation because Factor Analysis ordinarily does not have a traditional…

International Academy for Quality

*Recommendation

Year 2022

Quality improvement

An elite organization devoted to the promotion of quality initiatives in academia and industry. Note the link to the quality manifesto for the 21st Century.

RNA-Seq Analysis. Methods, Applications and Challenges

*Recommendation

Year 2022

Genomics analysis

This editorial provides a broad overview of a special issue on RNA-Seq analysis, a new approach for quantifying gene expression levels.

Mapping latitude and longitude

*Blog post

Year 2022

Geocoding

I’m trying to understand some of the basics of mapping and found an interesting example on [this website]

Philosophy emergency

*Recommendation

Year 2022

Critical appraisal

When I teach “Clinical Research Methodology,” I have to discuss the philosophical foundations of research. I am not a philosopher and have just a limited understanding of…

Progress on my website through the end of 2021

*Blog post

Year 2022

Website details

I spent much of Christmas break updating files from the year 2007. This was one of my most productive years. I developed presentations on children in research, open access…

Federated Learning and Privacy

*Recommendation

Year 2021

Data science

This article lays out the general principles of federated learning, a decentralized and privacy protecting approach to statistical modeling.

Uncovering Truths With Missing Data

*Recommendation

Year 2021

Data quality

The U.S. provides a rating system for nursing homes, but there are serious flaws in how this data is collected. In particular, many problems uncovered during government…

Why p-values are not measures of evidence

*Recommendation

Year 2021

Hypothesis testing

There are lots of criticisms of p-values, and while I don’t agree with all of them, it is important to understand these criticisms. This article discusses the definition of…

COSMIN methodology for evaluating the content validity of patient-reported outcome measures: a Delphi study

*Recommendation

Year 2021

Measuring agreement

This paper provides a nice checklist of itmes you should look for in a study establishing content validity ofr a patient-reported outcome measure.

Health Measurement Scales: A Practical Guide to Their Development and Use

*Recommendation

Year 2021

Measuring agreement

A nice comprehensive guide to the development of reliable and valid measurement scales in health care research. It is in its fifth edition; the version in my library is the…

Overfitting example using hurricane frequencies

*Blog post

Year 2021

Generalized linear model

Rmarkdown graphs

Overfitting occurs when a statistical model is too complex for the amount of data that it is based on. The summary statistics on the data itself appear to be quite good, but…

Dataset recommendations from the Journal of Statistics Education

*Blog post

Year 2021

Datasets

Teaching resources

The Journal of Statistics Education (now called the Journal of Statistics and Data Science Education) maintains an archive of interesting datasets. The data documentation is…

Dataset recommendations from statlib

*Blog post

Year 2021

Datasets

Teaching resources

A very old resource on the Internet with interesting datasets is statlib. The quality of the documentation is a bit uneven and some of the datasets are too simple to be used…

Joke about the dangers of extrapolation

*Blog post

Year 2021

Linear regression

There’s a joke I stole from the Internet, which you can find all over the place (here, here, and here). It is a humorous way of warning about the dangers of extrapolating…

Big Deal for Open Access

*Recommendation

Year 2021

Writing research papers

There is a lot of controversy about open access publishing and the University of California system inserted itself in the middle of the controversy when it canceled…

An overview of the National Health and Nutrition Examination Survey

*Blog post

Year 2021

Secondary data analysis

The National Health and Nutrition Examination Survey (NHANES) is a large scale survey conducted by the Centers for Disease Control and Prevention (CDC). It uses a complex…

Simply Statistics blog

*Recommendation

Year 2021

Graphical display

This is a nice professionally designed blog with no advertisements. The posts are fairly basic and accessible.

How many pages do I have in my website?

*Blog post

Year 2021

Website details

I am updating my website to a new format, and I want to keep track of how many pages have already been updated and how many still need to be updated. It’s tricky to get an…

Data Work. A Jargon-Free Guide to Managing Teams

*Recommendation

Year 2021

Human side of statistics

We get a lot of interesting people who show up at the Kansas City R User Group meetings. Taylor Rodgers is one of them. He is doing a lot of interesting work about how data…

Talk Stats

*Recommendation

Year 2021

Teaching resources

A wide range of questions from basic to advanced about Statistics, Probability, and Statistical Software.

History of Teacup Giraffes

*Recommendation

Year 2021

R software

Teaching resources

A very basic introduction to the R programming language.

We Are in Need of Data Ethics Now

*Recommendation

Year 2021

Ethics in research

Craig S. Mullins. We Are in Need of Data Ethics Now. Database trends and applicaitons, 2018-07-02. Available in html format. Approximately 1,400 words.

Basics of cubic spline models

*Recommendation

Year 2021

Linear regression

Rmarkdown graphs

Suppose you have some data where you suspect the behavior differs for x=1 to 5, x=6 to 10, x=11 to 15, and x=16 to 20.

Test diagrams

*Blog post

Year 2021

Graphical display

Rmarkdown graphs

An earlier version of this page was published on new.pmean.com.

The Integration of the Humanities and Arts with Sciences, Engineering, and Medicine in Higher Education

*Recommendation

Year 2021

Teaching resources

This report was recommended at a webinar I attended. I have not read the report yet, but the webinar mentioned several interesting and surprising ways that hihger education…

VALUE Rubrics

*Recommendation

Year 2021

Teaching resources

VALUE is an acronym for Valid Assessment of Learning in Undergraduate Education. This site provides rubrics for intellectual skills such as critical thinking and problem…

Very simple spline models

*Recommendation

Year 2021

Linear regression

Rmarkdown graphs

Suppose you want to fit a function that is flat from x=a to x=b and which declines linearly from x=b to x=c.

The dark side of big data

*Blog post

Year 2021

Data science

Incomplete page

Rmarkdown graphs

What’s all this reading about then

*Recommendation

Year 2021

Writing research papers

What does it mean to review the literature. This article digs into that question and offers a wealth of additional resources.

How to Share Your Research

*Recommendation

Year 2021

Writing research papers

THis article covers new changes in the publication process, including pre-prints and trial registration.

10 ingredients for a successful supervisor/PhD student relationship

*Recommendation

Year 2021

Human side of statistics

It’s important to provide guidance to a PhD candidate, and finding the right balance is important.

Survival of the best fit

*Recommendation

Year 2021

Data science

http://www.pmean.com/new-images/21/best-fit-simulation-01.png)

Ethical data science

*Recommendation

Year 2021

Ethics in research

Data science

A nice article talking about the importance of interpretability in data science.

Lead assessments in the NHANES survey

*Recommendation

Year 2021

Secondary data analysis

Here are some resources on the CDC website about NHANES, with special attention to lead assessments.

Diagnostics for a generalized linear model

*Blog post

Year 2021

Generalized linear model

Incomplete page

Rmarkdown graphs

There are a broad range of diagnostic methods (mostly graphical) that can help you decide from among a dizzying array of alternative models for count data. The most…

Journals Must Stop Exploiting Research for Profits

*Recommendation

Year 2021

Writing research papers

A harshly critical opinion piece about journals that expect free work from writers, editors, and reviewers, but then charges readers for access.

First steps with blogdown

*Blog post

Year 2021

Website details

Rmarkdown code

I am in the process of merging my website, written from 1999 to 2012 with my blog, which I started around 2012. I am using blogdown, an R package that creates a website from…

Progress in evidence-based medicine

*Recommendation

Year 2021

Health disparities

A nice summary of the changes (mostly improvements) in Evidence Based Medicine (EBM) over the past 25 years. It was written by two of the pioneers in EBM.

Health equity tourists: How white scholars are colonizing research on health disparities

*Recommendation

Year 2021

Health disparities

This article raises a difficult topic. While it is good that more white researchers are interested in health disparities research recently, some newcomers have marginalized…

Reading information from the American Community Survey into R

*Recommendation

Year 2021

Incomplete page

Rmarkdown graphs

Secondary data

Here is a simple example of how to read data from the American Community Survey into R.

LaTeX Math in Markdown

*Recommendation

Year 2021

Website details

I am having difficulty getting my website converted to blogdown. The latest problem is that all my math equations are not rendering properly. Yihui Xie suggests some reasons…

UMKC Faculty Researcher Award

*Blog post

Year 2021

Professional details

The UMKC School of Medicine has yearly awards that it hands out to faculty including a faculty researcher award. The awards allow for self-nomination, so I thought “Why not?”

Data Mining, Discovery and Exploration

*Recommendation

Year 2021

Data mining

This girhub repository has all the PowerPoint slides, handouts, and Python notebooks for a data mining course taught by Steve Elston of Harvard University. It is oriented…

Nursing Research, Step by Step

*Recommendation

Year 2021

Research design

This is a collection of articles (currently only five, but I suspect more will be added over time) that were published in the American Journal of Nursing. They cover some of…

Happy Git and GitHub for the useR

*Recommendation

Year 2021

R software

Software engineering

I have found that version control using git to be an integral part of my workflow. This website is an introduction of how to use git with R.

Direct standardization of mortality rates

*Blog post

Year 2021

Epidemiology

Incomplete page

Rmarkdown graphs

Mortality rates in different regions of the United States between different countries are dependent on the demographic distributions. Differences in the age distribution can…

Deviance in a generalized linear model

*Blog post

Year 2021

Generalized linear model

Rmarkdown graphs

Deviance is a measure computed for generalized linear models that can help you decide between two competing models. It is somewhat analogous to residual sums of squares in…

Quasi-likelihood models

*Blog post

Year 2021

Generalized linear model

Rmarkdown graphs

With the generalized linear model, you have the option of choosing a model that works well with a variety of different distributions (normal, Poisson, Gamma, etc.). But you…

Zero-inflated models

*Blog post

Year 2021

Generalized linear model

Incomplete page

Rmarkdown graphs

In models of counts, zeros represent a special case. Often there is more than one reason why you might observe a zero count, and you might want to model this probability…

Working with negative binomial regression

*Blog post

Year 2021

Probability distributions

Generalized linear model

Rmarkdown graphs

The negative binomial distribution is similar to the Poisson distribution, but it offers a bit more flexibility. This page will review some basic properties of the negative…

Working with the Poisson distribution

*Blog post

Year 2021

Incomplete page

Probability distributions

Rmarkdown graphs

Many statistics, such as mortality statistics, are based on fundamental counting processes. If you want to understand these processes, you should start by trying to…

Working with Poisson regression

*Blog post

Year 2021

Probability distributions

Rmarkdown graphs

Poisson regression is a statistical model under the large umbrella of generalized linear models. I want to explain how Poisson regression works. I also will show and…

Shape-Restricted Regression Splines with R Package splines2

*Recommendation

Year 2021

Linear regression

Splines allow you to fit an almost infinitely flexible number of nonlinear curves, but sometimes you want to place restrictions, such as monotonicity or periodicity on those…

Show me the data

*Recommendation

Year 2021

Critical appraisal

Inadequate data on the COVID-19 pandemic has hindered our ability to make the right decisions about prevention and treatment.

Real-world String Comparison

*Recommendation

Year 2021

Statistical computing

A nice article that talks about the problems with comparing strings when multi-byte Unicode characters are used.

Asking great questions

*Recommendation

Year 2021

Human side of statistics

Eric Vance has done a lot of work about improving the process of statistical consulting. This talk was presented at the 2021 Joint Statistics Meetings and explained that…

Two resources for getting started in statistical consulting

*Recommendation

Year 2021

Human side of statistics

While looking for some materials on my site, I found a couple of things that others had written about getting starting in the business of statistical consulting.

Efforts of biostatisticians in research

*Recommendation

Year 2021

Human side of statistics

I attended a talk on the special issues facing biostatisticians in academic positions. The speaker shared three interesting documents about how to evaluate statistical…

The Vancouver Recommendations

*Recommendation

Year 2021

Writing research papers

This is a consensus document created by a group of journal editors who met in Vancouver in 1978. This has been updated regularly. It covers authorship guidelines on…

Speaking R

*Recommendation

Year 2021

R software

Teaching resources

An hour long video, but worth watching for anyone who teaches programming, but especially anyone who teaches R. The general thesis is that you should speak the code as you…

The Precis-2 toolkit

*Recommendation

Year 2021

Research design

A nice guide for assessing the degree to which a clinical trial is pragmatic. It uses a nine item scale that is intuitive and easy to apply. There is also a website that…

R Open Science

*Recommendation

Year 2021

R software

R OPen Science is a team effort to develop a systematic process to develop and test R packages. The team has a web site, a book, and a software review system.

Resources for spatial statistics

*Recommendation

Year 2021

R software

I attended a talk on recent developments in spatial statistics and while most of the talk was over my head, I did not some resources in the introduction that might be…

Resources for AI Fairness

*Recommendation

Year 2021

Data science

The Joint Statistics Meetings had a great talk on Fairness in Artifical Intelligence (AI). The speaker, Sherrie Rose, documented instances where AI has had a discriminatory…

Developing and Maintaining Open Source Resources for Statistics and Data Science Education

*Recommendation

Year 2021

Teaching resources

This website provides the slides and other resources associated with a session at the 2021 Joint Statistics Meetings on open source education resources.

Julia for Statistics and Data Science

*Recommendation

Year 2021

Julia programming

Doug Bates gave an excellent talk at the 2021 Joint Statistics Meetings about Julia, a new programming language that tries (and to a large extent succeeds) to be both…

Special Issue on Statistical Practice

*Recommendation

Year 2021

Writing research papers

The journal STAT (not the medical term for immediately, but rather an abbreviation of the word, Statistics) will be calling for a special issue on Statistical Practice. The…

Learning more about SAS

*Blog post

Year 2021

SAS software

A student in my Introduction to SAS class (MEDB 5507) asked a question that was difficult to answer, but also important to answer. The student wanted to know “a good…

How to Choose the Journal That’s Right for Your Study

*Recommendation

Year 2021

Writing research papers

An easy to read guide on picking the right journal to send your publication to.

Kaggle, 80 cereals

*Recommendation

Year 2021

Datasets

I’m always on the lookout for simple but interesting datasets. This one provides nutritional informaton on 80 different cereal products.

Broadcom in talks to buy SAS for as much as $20B

*Recommendation

Year 2021

SAS software

SAS Institute is a privately held company and the two owners are both getting old. So this report about a possible purchase of SAS by an outside group is an interesting…

Cel-Sci CEO tries to spin cancer trial failure into a win

*Recommendation

Year 2021

Human side of statistics

It is unusual for issues like p-value hacking to make it into our court system. It is unpredictable how judges will react to some rather technical arguments..

Introduction to Formulaic

*Recommendation

Year 2021

R software

This R package automates an important part of model building: creating formula objects.

Mapping R functions

*Recommendation

Year 2021

R software

In a large R program, you might lose track of how functions that you wrote relate to one another. This program examines those relationships and produces an adjacency matrix.

Metadata vignette

*Recommendation

Year 2021

R software

Reproducible research

This package has a collection of functions that lets you create information about a dataset in R and store that information as an attribute. This makes it easier for you to…

The obesity wars and the education of a researcher

*Recommendation

Year 2021

Human side of statistics

Some areas of research are quite contentious and when you publish an article that angers advocates on one side or the other of an issue, you may find yourself the talk of…

R Package for Adaptive Clinical Trials

*Recommendation

Year 2021

Bayesian statistics

R software

A nice introduction to a package for group sequential designs using Bayesian methods.

Types of Statistics Papers

*Recommendation

Year 2021

Writing research papers

A humorous cartoon about research topics in Statistics.

R Packages

*Recommendation

Year 2021

R software

A great resource if you want to develop a package in R. You can buy this book, or read it for free.

Basic Python Resources

*Blog post

Year 2021

Python programming

I’m trying to learn Python, and a recent short course (Data Scientist’s Workflow: EDA and Statistical Modeling with Python in Jupyter Noteboos workshop, taght by Chris…

Anonymizing ids

*Blog post

Year 2021

Privacy in research

Rmarkdown code

I’m working on a project that might be exempt from IRB review…if I can convert a particular ID code to an anonymous code. The ID codes are an eight digit number. Here’s a…

Statistical Thinking

*Recommendation

Year 2021

Teaching resources

Frank Harrell is a very opinionated statisticians, and his opinions are almost always on the mark. He’s shaped the discipline of Statistics in many ways over a career that…

S, R, and data science

*Recommendation

Year 2021

R software

John Chambers is one of the creators of the S programming language,a pre-cursor to R. In this article, he describes how both R and S were developed with goal of advancing…

Finally, a proven method to show just how funny I am

*Recommendation

Year 2021

Data science

A satirical look at sentiment analysis–in particular, the use of sentiment analysis to identify “the funniest movies ever made.”

Songs by Tom Lehrer (1953), Lobachevsky

*Recommendation

Year 2021

Ethics in research

A cute song by famous satirist, Tom Lehrer, on the secret of success in research. Plagiarism!

Choosing a good chart

*Recommendation

Year 2021

Graphical display

A simple guide for choosing among a variety of different visualization methods. These are mostly basic charts, such as pie charts, histograms, and pie charts. I don’t agree…

The illusion of predictability. How regression statistics mislead experts

*Recommendation

Year 2021

Human side of statistics

The authors argue that regression models fail to capture important levels of uncertainty needed for economic decisions.

Reference Collection to push back against Common Statistical Myths

*Recommendation

Year 2021

Teaching resources

There are some commonly used statistical methods (e.g., post hoc power, stepwise regression) which are widely criticized in the Statistics literature. If you run across one…

An introduction to the Poisson bootstrap

*Recommendation

Year 2021

Bootstrap

An interesting approach to the Bootstrap that can handle big data in a single pass, even if you don’t know the number of observations in the data set or the data is split…

Downweighting informative prior distributions

*Blog post

Year 2021

Bayesian statistics

There are a variety of approaches to handle informative prior distributions when they disagree sharply with the data. I want to summarize a few papers that present these…

COMPAS Recidivism Risk Score Data and Analysis

*Recommendation

Year 2021

Data science

The data behind a classic article about algorithmic bias.

Experimental Evaluation of Algorithm-Assisted Human Decision-Making: Application to Pretrial Public Safety Assessment

*Recommendation

Year 2021

Data science

Cutting edge research on algorithms and how they affect human biases.

Alluvial Plots in ggplot2

*Recommendation

Year 2021

Graphical display

Alluvial plots show streams of different colors that show how certain categorical variables interrelate. I am not sure that the graphs are all that effective, but if you…

Changing and modifying a Hugo theme on your R Blogdown site

*Recommendation

Year 2021

Graphical display

A nice very detailed blog post about how to change to a different Hugo theme within blogdown and how to adapt that theme to your special requirements.

Heterogeneity introduced by EHR system implementation in a de-identified data resource from 100 non-affiliated organizations

*Recommendation

Year 2021

Electronic health records

A nice illustration of how chaotic electronic health record data can be when aggregated across a large number of hospitals.

Replication Crisis

*Recommendation

Year 2021

Critical appraisal

This is a review of a book by Stuart Ritchie (Science Fictions: Exposing Fraud, Bais, Negligence, and Hype in Science) that offers a very bleak picture of the world of…

A roadmap to using historical controls in clinical trials

*Recommendation

Year 2021

Graphical display

More and more new drug applications are relying on historical controls, but this must be done carefully. This paper outlines the reasons why you might want to use historical…

Upset plot, the R Graph Gallery

*Recommendation

Year 2021

Graphical display

While Venn diagrams can illustrate how much overlap there is among two or three groups, it becomes more complex when you have a lot more than three groups. The upset plot is…

Police Killings dataset

*Recommendation

Year 2021

Datasets

The data is from 2015, which makes it a bit dated, but this is an interesting dataset with information from a British newspaper, The Guardian, combined with information from…

Amazon scraps secret AI recruiting tool that showed bias against women

*Recommendation

Year 2021

Data science

This is a cautionary article about how machine learning models can lead to unintended discriminatory hiring policies.

Ethical AI: A Framework for Justice

*Recommendation

Year 2021

Data science

This is a cautionary article about how machine learning models can lead to unintended discriminatory hiring policies.

Issues with data and analyses. Errors, underlying themes, and potential solutions

*Recommendation

Year 2021

Critical appraisal

One of my students showed me this paper. It looks at errors in research and tries to array them into a broad set of themes. This is a very ambitious effort and, at first…

Journal of Clinical and Translational Science

*Recommendation

Year 2021

Writing research papers

At a Zoom meeting today, someone mentioned an interesting journal that appears to talk a lot about the research process. It is particularly targeted to medical research and…

Enabling Reproducible Research: Open Licensing for Scientific Innovation

*Recommendation

Year 2021

Data sharing

This paper argues that U.S. Copyright law is a barrier to the sharing of computer code and datasets. She proposes an alternative, the Reproducible Research Standard that…

Papers with code

*Recommendation

Year 2021

Data sharing

This site promotes the sharing of code and data with research publications and offers links to articles that make their code and data freely available.

Census Data Processing 101

*Recommendation

Year 2021

Bureau of the Census

The data collected as part of the decennial U.S. Census comes from a variety of sources and it all needs to be combined. This article provides a simple and easy to follow…

Making the CECPfuns package: my own usable package

*Recommendation

Year 2021

R software

There is a specific structure that you must follow if you want to develop a package in R. This blog post shows a very simple skeleton package with a single R function and…

Final.doc

*Recommendation

Year 2021

Writing research papers

This comic shows the peril of using the word “final” in the name of a file. You will find that you have to make changes that invalidate the finalness of your filename.

The documentation system

*Recommendation

Year 2021

Software engineering

This site was recommended at a webinar I attended on teaching computing skills in a Statistics/Data Science class. Documentation can be split into four different categories…

Help for teaching statistical computing skills

*Blog post

Year 2021

Teaching resources

I attended an interesting webinar on teaching statistical computing skills. The seminar touched on one key paper written in 2010 and a special issue of The Journal of…

An Undergraduate Bayesian Statistics Course

*Blog post

Year 2021

Teaching resources

I attended an interesting webinar on teaching undergraduate Bayesian STatistics courses. Here are some resources I found out about during the webinar. I am putting them here…

Five years of Raspberry Pi clusters

*Recommendation

Year 2021

Cluster computing

I have been interested for quite a while in running a cluster computer using Rapsberry Pis and running software like Spark. Unfortunately, I have been too busy to work on…

How to save RMarkdown output in the results folder

*Blog post

Year 2021

R software

I have a directory structure for most projects that is based on the recommendations in Wilson et al. In particular, I store program code in the src folder and output in the…

How to run SAS inside an RMarkdown file

*Blog post

Year 2021

R software

I create a lot of teaching resources using R Markdown. A question arises about how to incorporate SAS code and output into these teaching resources. I had written earlier…

National Institute of Statistical Sciences

*Recommendation

Year 2021

Teaching resources

The National Institute of Statistical Sciences (NISS) is a consortium of high level researchers in Statistics who develop new methodologies and training solutions. I have…

Smart Tracker

*Recommendation

Year 2021

SQL

I am working with a reasearch team that needs to track a variety of public health outcomes involving testing and vaccination. They are considering a data collection and…

Child documents. Input child document into the main document

*Recommendation

Year 2021

R software

This is part of the documentation for knitr, a package in R. It shows how to include one or more Rmarkdown files inside a master Rmarkdown file.

SASWeave: Literate Programming Using SAS

*Recommendation

Year 2021

SAS software

Russ Lenth has developed a nice system that integrates SAS code and SAS output within a TeX file. This provides a nice way to teach SAS, as you see the SAS code next to the…

Tidy Modeling with R

*Recommendation

Year 2021

Statistical models

Max Kuhn and Julia Slige present a detailed tutorial on some recent advances in R that help you build the best statistical model for your data. This includes the difficult…

I have too many github repositories

*Blog post

Year 2021

Statistical computing

After many presentations at the Kansas City R Users Group, I decided a couple of years ago to do most of my R programming with github as the version control system. Perhaps…

Today’s False Prophets

*Recommendation

Year 2021

Human side of statistics

Ben Chugg article defines a term, cliodynamics, as the effort to predict future political and societal events based on past history. He then explains why this process is…

RCT-DUPLICATE

*Recommendation

Year 2020

Observational studies

Reproducible research

This project is a collaborative effort to find clinical trials used in regulatory decision making and replicate the results using real-world evidence (observational studies…

Precisely the opposite of what we now know to be true

*Quotation

Year 2020

Reproducible research

Dr. Melik: This morning for breakfast he requested something called “wheat germ, organic honey, and tiger’s milk.”

Reproducibility and Replicability in Science

*Recommendation

Year 2020

Reproducible research

This book, produced by the National Academy of Sciences, Engineering, and Medicine, is available for free as a large PDF file, or for purchas as a paperback book or ebook.…

How can you learn R?

*Blog post

Year 2020

R software

I get this question a lot: How do I learn how to use R? I usually mumble something, and feel quite uncomfortable. In fact. It is not easy to learn R on your own. It is not…

COVID-19 open source data sets

*Recommendation

Year 2020

Datasets

Teaching resources

Shuja, J., Alanazi, E., Alasmary, W. et al. COVID-19 open source data sets: a comprehensive survey. Appl Intell (2020). DOI: 10.1007/s10489-020-01862-6. Available in html…

Advice From Blind Teachers on How to Teach Statistics to Blind Students

*Recommendation

Year 2020

Teaching resources

A. Jonathan R. Godfrey and M. Theodor Loots. Advice From Blind Teachers on How to Teach Statistics to Blind Students. Journal of Statistics Education 2015, 23(3). Available…

The tidy tools manifesto

*Recommendation

Year 2020

R software

Hadley Wickham. The tidy tools manifesto. 2019-11-19. Available in html format.

How I use R Markdown to write research papers

*Blog post

Year 2020

R software

Rmarkdown graphics

Writing research papers

I joined a writing group at UMKC and am making very good progress on a couple of research papers. The group meets once a week to talk about everyone’s progress and to share…

Advice for a beginner Bayesian

*Blog post

Year 2020

Bayesian statistics

I was asked for some advice about how to get started with Bayesian data analysis. This person had taken a course on this topic, but did not know how to use he learned on a…

Generalized Linear Models

*Recommendation

Year 2020

Datasets

German Rodriguez. Generalized Linear Models. Datasets. Available in html format.

Complementary Log-Log Model for Interval-censored Survival Times

*Recommendation

Year 2020

Survival analysis

SAS Institute. Example 39.11: Complementary Log-Log Model for Interval-censored Survival Times. Available in html format.

Election Maps Are Everywhere. Don’t Let Them Fool You.

*Recommendation

Year 2020

Graphical display

Betsy Mason. Election Maps Are Everywhere. Don’t Let Them Fool You. The New York Times 2020-10-30. Available in html format.

Disappearing Data

*Recommendation

Year 2020

Government statistics

An account of recent events to stop the collection of data that the current administration thinks might hurt some of its efforts to roll back regulations.

The Evolution of Data Science … As I Remember It

*Recommendation

Year 2020

Data science

Charlie Kufs. The Evolution of Data Science … As I Remember It. Stats with Cats blog 2020-10-22. Available in html format.

Making genome data come alive with circos plots

*Recommendation

Year 2020

Graphical display

Maria Nattestad. Making genome data come alive with circos plots. Medium 2017-09-25. Available in html format.

Basic notation for survival or time-to-event analyses

*Blog post

Year 2020

Survival analysis

I got some questions about the notation I use for various functions in survival models and the interpretation of some of these functions.

Bias in Bias Recognition

*Recommendation

Year 2020

Critical appraisal

Qi Wang, Hee J. Jeon. “Bias in Bias Recognition: People View Others but Not Themselves as Biased by Preexisting Beliefs and Social Stigmas.” PsyArXiv, 2020-02-27. Available…

Excel: Why using Microsoft’s tool caused Covid-19 results to be lost

*Recommendation

Year 2020

Data management

Leo Kelion. Excel: Why using Microsoft’s tool caused Covid-19 results to be lost. BBC News 2020-10-06. Available in html format.

How I got started in Evidence-Based Medicine

*Blog post

Year 2020

Evidence-Based Medicine

I am working with a new group looking at early childhood interventions, and they want my advice about a variety of issues related to Evidence-Based Medicine (EBM). Why would…

A New Standard For Publishing On Racial Health Inequities

*Recommendation

Year 2020

Evidence-Based Medicine

Schunemann HJ, Santesso N, Vist GE, et al. Using GRADE in situations of emergencies and urgencies: certainty in evidence and recommendations matters during the COVID-19…

Philosophy of Data Science | Welcome to the Series!

*Recommendation

Year 2020

Data science

Glen Wright Colopy. Philosophy of Data Science | Welcome to the Series! Youtube 2020-09-16. Available in video format.

Stats + Stories

*Recommendation

Year 2020

Podcasts

A. John Bailar. Stats + Stories. Available in html format.

Warning: Physics Envy May be Hazardous to Your Wealth

*Recommendation

Year 2020

Critical appraisal

Lo AW, Mueller MT. Warning: Physics Envy May be Hazardous to Your Wealth! SSRN 2019-03-12. Available in PDF format.

Research interests

*Blog post

Year 2020

Professional details

I have been asked to present a bit of information about my research interests to the students in the Graduate Research Seminar for the Department of Biomedical and Health…

Biopharmaceutical Section Offers Advice for ASA Fellow Nomination

*Recommendation

Year 2020

Professional details

Alex Dmitrienko, Ilya Lipkovich, and Paul Gallo. Biopharmaceutical Section Offers Advice for ASA Fellow Nomination. Amstat News 2020-06-01. Available in html format.

Wavelet Pooling for Convolutional Neurual Networks

*Recommendation

Year 2020

Data science

Travis Williams, Robert Li. Wavelet Pooling for Convolutional Neurual Networks. Published as a conference paper at ICLR 2018. Available in pdf format.

Statisticians React to the News

*Recommendation

Year 2020

Human side of statistics

International Statistical Institute. Statisticians React to the News. Available in html format.

AI Fairness 360 Open Source Toolkit

*Recommendation

Year 2020

Data science

IBM. AI Fairness 360 Open Source Toolkit. Available in html format.

Relationship Between Total and Bioaccessible Lead on Children’s Blood Lead Levels in Urban Residential Philadelphia Soils

*Recommendation

Year 2020

Datasets

Teaching resources

Bradham KD, Nelson CM, Kelly J, et al. Relationship Between Total and Bioaccessible Lead on Children’s Blood Lead Levels in Urban Residential Philadelphia Soils. Environ Sci…

A New Standard For Publishing On Racial Health Inequities

*Recommendation

Year 2020

Racial disparities

Rhea W. Boyd Edwin G. Lindo Lachelle D. Weeks Monica R. McLemore. On Racism: A New Standard For Publishing On Racial Health Inequities. Health Affairs 2020-07-02. doi…

Envisioning a Transformed Clinical Trials Enterprise in the United States

*Recommendation

Year 2020

Clinical trials

nstitute of Medicine. 2012. Envisioning a Transformed Clinical Trials Enterprise in the United States: Establishing an Agenda for 2020: Workshop Summary. Washington, DC: The…

Setting the Stage: Statistical Collaboration Training Videos

*Recommendation

Year 2020

Human side of statistics

Julia Sharp, Emily Griffith, and Megan Higgs, Ann Hess. Setting the Stage: Statistical Collaboration Training Videos. Available in html format.

Upload data from R to an HTML page with rmarkdown and ftpUpload

*Recommendation

Year 2020

R software

Linus Larsson. Upload data from R to an HTML page with rmarkdown and ftpUpload, Linus Larsson’s Blog - Data Science and Analytics, 2019-05-16. Available in html format.

Filed under: The differences

*Recommendation

Year 2020

Human side of statistics

Paul Dauenhauer. Tweet, 2020-08-14. Available in html format.

Data 8: The Foundations of Data Science

*Recommendation

Year 2020

Data science

University of California/Berkeley. Data 8: The Foundations of Data Science. Available in html format.

Simple Demographics Often Identify People Uniquely

*Recommendation

Year 2020

Data science

Ethics in research

Kaiyu Yang, Klint Qinami, Li Fei-Fei, Jia Deng, Olga Russakovsky. Towards Fairer Datasets: Filtering and Balancing the Distribution of the People Subtree in the ImageNet…

Simple Demographics Often Identify People Uniquely

*Recommendation

Year 2020

Ethics in research

Latanya Sweeney. Simple Demographics Often Identify People Uniquely. Carnegie Mellon University, Data Privacy Working Paper 3. Pittsburgh 2000. Available in pdf format

Any sufficiently advanced math

*Quotation

Year 2020

Data science

Some context is in order here. The quote is a take-off on Arthur C. Clarke’s famous quote: “Any sufficiently advanced technology is indistinguishable from magic.”…

Health statistics represent

*Quotation

Year 2020

Human side of statistics

An earlier version is here.

Biography for a research grant

*Blog post

Year 2020

Professional details

When you help write up a research grant, you need to brag about how smart and talented you are. I am not shy about promoting myself, so this is pretty easy for me to do.…

The ASCCR Frame for Learning Essential Collaboration Skills

*Recommendation

Year 2020

Professional details

Eric A. Vance, Heather S. Smith. The ASCCR Frame for Learning Essential Collaboration Skills. Journal of Statistics Education 2019-09-02. 27(3): 265-274. doi…

How to be more effective in your professional life

*Recommendation

Year 2020

Human side of statistics

Doug Zahn, How to be more effective in your professional life. Amstat News, 2009 09 01. Available in html format

Getting science published

*Recommendation

Year 2020

Writing research papers

Kathryn Everson. Friends! Did you know that legitimate scientists publish their research in academic journals? Flickr 2020-05-13. Available in html format.

The Scientist’s Guide to Poster Design

*Recommendation

Year 2020

Presenting research

Kathryn Everson. The Scientist’s Guide to Poster Design. Available in html format.

Data for Black Lives

*Recommendation

Year 2020

Data science

Yeshimabeit Milner, Lucas Mason-Brown, Jamelle Watson-Daniels, Stacy Jebett Bullard, Nicole Triplett. Data for Black Lives. Available in html format.

AMS Style Guide

*Recommendation

Year 2020

Writing research papers

Mary Letourneau, Jennifer Wright Sharp. AMS Style Guide. Journals. American Mathematical Society 2017. Available in pdf format.

Aleatory and epistemic uncertainties can completely derail medical research results

*Recommendation

Year 2020

Critical appraisal

Incomplete page

Note: the name of this page needs to reflect the topic.

Attack on statistical significance: A balanced approach for medical research

*Recommendation

Year 2020

Hypothesis testing

Abhaya Indrayan. Attack on statistical significance: A balanced approach for medical research. Indian Journal of Medical Research 2020. 151(4): 275-278. doi…

The Human Experience Will Not Be Quantified

*Recommendation

Year 2020

Human side of statistics

Phil Klay. The Human Experience Will Not Be Quantified. Why do we keep mistaking data for knowledge? The New York Times, 2020-11-07. Available in html format.

Florida fired its coronavirus data scientist. Now she’s publishing the statistics on her own.

*Recommendation

Year 2020

Data mining

The COVID-19 crisis has caused a lot of contention over issues that normally would be ignored by everyone except a few specialists. As an example, Rebekah Jones was a data…

Tests of trend between disease outcomes and ordinal covariates discretized from underlying continuous variables

*Recommendation

Year 2020

Ordinal data

Brownstein, N.C., Cai, J. Tests of trend between disease outcomes and ordinal covariates discretized from underlying continuous variables: simulation studies and…

How to Call B.S. on Big Data.

*Blog post

Year 2020

Data science

Michelle Nijhuis. How to Call B.S. on Big Data. A Practical Guide. The New Yorker. 2017-06-03. Approximately 1,300 words. Available in html format

Constructing sound science and good epidemiology: tobacco, lawyers, and public relations firms

*Recommendation

Year 2020

Observational studies

Ong EK, Glantz SA. Constructing “sound science” and “good epidemiology”: tobacco, lawyers, and public relations firms. Am J Public Health. 2001;91(11):1749-1757.…

Steve Milloy misfires

*Recommendation

Year 2020

Critical appraisal

Observational studies

Lambert T. Steve Milloy misfires. Science Blogs 2004-09-03. Available in html format.

In medicine, there is automatic

*Quotation

Year 2020

Observational studies

In [medicine] there is automatic downgrading of observational studies below randomized (no matter how fine the former or irrelevant the latter - med RCTs are notorious for…

The Bioconductor library of packages for R

*Blog post

Year 2020

R software

Back in the previous decade, I spent a lot of time working on the various statistical methods required for genetics studies. It was difficult, but fun. For a variety of…

The tendency of some modelers

*Quotation

Year 2020

Critical appraisal

“The tendency of some modelers to present them as scientific predictions of the future rather than models does not help. Models are widely used in government, and some…

Reading text files

*Blog post

Year 2020

Data management

Rmarkdown code

Many data files stored on the Internet use text format. Here is an explanation of what text format is and how you can read it into a program for data analysis.

An incomplete list of data repositories

*Blog post

Year 2020

Teaching resources

This is a partial list of data repositories where you can store the datasets associated with your peer-reviewed publications. I am interested in assistance with this…

Criticisms of the IHME COVID-19 model

*Blog post

Year 2020

Epidemiology

Rmarkdown graphs

This blog post was created on 2020-04-23 and last modified on 2025-08-23.

Codes for COVID-19 in the electronic health record

*Blog post

Year 2020

Electronic health records

I might be helping with a research project that involves selection of medical records associated with COVID-19. Here are some of the resources and suggestions that I…

Analyzing ordinal data with metric models: What could possibly go wrong?

*Recommendation

Year 2020

Likert scales

Torrin M. Liddell and John K. Kruschke. Analyzing ordinal data with metric models: What could possibly go wrong? Journal of Experimental Social Psychology 2018. 79: 328 -…

Different map projections

*Blog post

Graphical display

I have been drawing some maps in R and was struggling to figure out how to display things with the appropriate map projections. Here is some code where I experimented with a…

An example of a poor color choice

*Blog post

Year 2020

Graphical display

Rmarkdown graphs

I ran across a graph in a journal article. The article itself was good, but the graph had a rookie mistake. I shouldn’t point this out, because I myself have been guilty of…

UMKC big data and data science initiatives

*Blog post

Year 2020

Data science

I am trying to keep track of several recent initiatives at UMKC. Here are the details, as I best understand them.

Food inspections

*Recommendation

Year 2020

Datasets

City of Albuquerque. Food inspections. Available in html format.

Barbershop music

*Recommendation

Year 2020

Datasets

Data Description. Barbershop Music. Available in text format.

Smart quotes, em dashes, and en dashes

*Blog post

Year 2020

Data management

Rmarkdown code

If you work with text data a lot, you will encounter some characters that are sort of close to what you need, but sort of not. These include the smart quotes, em dashes, and…

Proposed talk on secondary data analysis

*Blog post

Year 2020

Observational studies

I am suggesting a talk on secondary data analysis for a seminar series here at UMKC. Here is the title and abstract.

No aphorism is more frequently repeated

*Quotation

Year 2020

Research design

“No aphorism is more frequently repeated in connection with field trials, than that we must ask Nature few questions, or, ideally, one question, at a time. The writer is…

Data collection in a research methods class

*Blog post

Year 2020

Teaching resources

One of the discussion boards sponsored by the American Statistical Association had a question about data collection exercises in a research methods class. The initial…

Data visualizaiton as art

*Blog post

Year 2020

Graphical display

I came across an interesting article in the New York Times and two books that all have a common theme. They use the tools of data visualization to make artistic statements.

Printing R Markdown output to png files

*Blog post

Year 2020

R software

I have been using a tedious process to convert parts of the output of an R Markdown file to png files. I want to use png files because they can be inserted easily into a…

Artist wanted, here are the details

*Blog post

Year 2020

Ethics in research

I have gotten several nibbles on a posting that I made last week. Here is some more information.

Celebrating the failures of medical research using a graphic novel format

*Blog post

Year 2020

Ethics in research

I sent out a flurry of small grants in December and most did not get funded, but one of them did. And I need your help with finding the right collaborator.

Imbalanced sample sizes in the Fisher Exact test

*Blog post

Year 2020

Measuring benefit and risk

Dear Professor Mean, We are conducting a study in which mice receive one of four different injections (various combinations of hormones and receptor antagonists)receive a…

Identifying and manipulating non-breaking spaces

*Blog post

Year 2020

Data management

Rmarkdown code

Non-breaking spaces are one of those weird little things in the computer that you have to keep your eye on. They can cause a lot of problems if they are assumed to be normal…

Finding me on the Internet

*Blog post

Year 2019

Professional details

It is worth tracking the limited number of websites that mention me (and not people who share my first and last name). Here are a few places where I get mentioned, albeit…

PROC-X.com. An online (unofficial) SAS journal – written by bloggers

*Recommendation

Year 2019

SAS software

A nice site that aggregates blog posts about SAS from a variety of authors.

Scientists’ grant writing styles vary by gender

*Recommendation

Year 2019

Grant writing

This is a brief summary of a research paper (apparently behind a pay wall, boo!) that looked at the language used in research grants submitted to the Gates Foundation. It…

Assessment Resource Tools for Improving Statistical Thinking

*Recommendation

Year 2019

Teaching resources

A great teaching resource with a test bank of items to assess knowledge and attitudes about Statistics. There are also links to other helpful resources.

Several Python resources

*Blog post

Year 2019

Python programming

I have not had the time to learn Python yet, but it is on my short term list of research goals. I attended a very nice talk about Python and data science and tried to get a…

Data science curriculum roadmap

*Recommendation

Year 2019

Data science

Teaching resources

How do you teach data science? That’s not an easy question because data science means different things to different people. This site shows different curricula depending on…

A tribute to Douglas C. Altman, DSc

*Recommendation

Year 2019

Important statisticians

This a brief and personal recollection of Doug Altman, a statistician who has had great influence in the practice of Statistics and the reporting of research results. There…

Writing the methods section of a research paper

*Blog post

Year 2019

Writing research papers

I’m teaching a class on Clinical Research Methodology and at least a few of the students are confused about what to put in the methods section of a research paper or a…

Bibliographies and citations (in R Markdown)

*Recommendation

Year 2019

Presenting research

R software

Writing research papers

If you want to use R Markdown to prepare research papers and presentations, you need to learn how to cite references and include a bibliography. This is a nice introduction…

Separating Unique and Duplicated Observations Using PROC SORT in SAS 9.3 and Newer Versions

*Recommendation

Year 2019

Data management

SAS software

SAS has some very powerful ways to find duplicate values and to store the duplicates separate from the unique values. Many of these use the sort procedure. Here is a nice…

What would Florence Nightingale make of big data?

*Recommendation

Year 2019

Data science

This is a nice video, professionally produced and very short (4 minutes) that shows the importance Florence Nightingale attached to Statistics. It reviews how she used…

When Big Data goes to school

*Recommendation

Year 2019

Data science

File this under the “dark side” of data science. Alfie Kohn is a critic of many of the motivational methods used in business and education, and he makes many good points in…

Writing a discussion section: how to integrate substantive and statistical expertise

*Recommendation

Year 2019

Writing research papers

The paper in BMC Medical Research Methodology gives practical step by step guidance on writing your discussion section.

Copyright and Data

*Recommendation

Year 2019

Data sharing

This is a nice one page document on copyright issues associated with research data and how to best share your research data with others.

Case for omitting tied observations in the two-sample t-test and the Wilcoxon-Mann-Whitney Test

*Recommendation

Year 2019

Nonparametric tests

When you are running a non-parametric test, like the Wilcoxon-Mann-Whitney test, you can only be 100% certain of the properties of that test (including Type I and Type II…

When life gives you coloured cells, make categories

*Recommendation

Year 2019

Data management

A lot of people use formatting to denote important information in an Excel spreadsheet. In particular, they will use the color of a cell to designate a particular category.…

Ethical Practice in Data Mining

*Blog post

Year 2019

Data science

This is a very nice summary of six major areas where data mining has led to serious ethical concerns.

Writing the introduction section of a research thesis or dissertation

*Blog post

Year 2019

Writing research papers

The introduction section of your research thesis or dissertation is the first thing that most people will read after reading the abstract. Some people use the introduction…

Census Geocoder

*Recommendation

Year 2019

Geocoding

This website will take an address, either on a form or as a batch of up to 10,000 addresses (CSV format) and provide latitude, longitude pairs as well as U.S. Census tract…

Data Science Has Become About Lending False Credibility To Decisions We’ve Already Made

*Recommendation

Year 2019

Data science

A rather harsh and cynical take on data science, but still worth reading. Let me share a story about this. Back in my college days (that would be the 1970s), someone found a…

Harvard University Program on Survey Research

*Recommendation

Year 2019

Survey design

This is a series of guides on survey research, written for the beginning student. It is written from the perspective of Political Science, but the advice works for other…

A systematic review shows no performance benefit of machine learning over logistic regression for clinical prediction models

*Recommendation

Year 2019

Data science

Logistic regression

Systematic overviews

This is one of those articles where you have to restrain yourself. Its message - that good old statistical tools like logistic regression can perform as well as these new…

Webinar Series, Congressionally Directed Medical Research Programs

*Recommendation

Year 2019

Grant writing

We live in a golden age of learning, where you find find just about anything you’d ever need to learn from on the Internet. One example of this is a series of webinars about…

LaTeX/Mathematics

*Recommendation

Year 2019

Presenting research

R software

Writing research papers

You can incorporate very nice looking mathematical formulas in R Markdown fairly easily. The system relies on LaTeX for displaying formulas and is surprisingly easy to…

Did you hear about the mathematician

*Quotation

Year 2019

Numbers

“Did you hear about the mathematician who was afraid of negative numbers? He would stop at nothing to avoid them.” (This joke is all over the Internet, and I’m not sure…

R Markdown Basics

*Recommendation

Year 2019

R software

Writing research papers

This is actually a nice “peek under the hood” approach with lots of practical advice about getting that last tweak in to make your results go from good to great.

Stop Saying ‘Exponential.’ Sincerely, a Math Nerd.

*Recommendation

Year 2019

Critical appraisal

This is a brief plea to avoid using the word “exponential” when you really mean “a lot.”

12 things I wish I’d known before starting as a Data Scientist

*Recommendation

Year 2019

Human side of statistics

This article was recommended to me at a webinar I attended. The author offers very personal and practical advice. The author’s third point “You’ll never have to know all the…

Slapping the word pilot on a failed study

*Blog post

Year 2019

Early stopping

Pilot studies

Someone was asking on the MedStats listserv about a study that had gone off the rails. They had recruited only about a third of the patients that they had wanted. Things…

All scientific work is incomplete

*Quotation

Year 2019

Critical appraisal

Observational studies

“All scientific work is incomplete - whether it be observational or experimental. All scientific work is liable to be upset or modified by advancing knowledge. That does not…

Make a loud mistake

*Blog post

Year 2019

Grant writing

Research design

Writing research papers

I dated a piano major in college and I tried - with very limited success, to learn how to play the piano myself. She told me - “If you’re going to make a mistake - make a…

How to Use Deming’s 14 Points to Improve Quality

*Recommendation

Year 2019

Quality improvement

This blog post provides a few short paragraphs elaborating on each of W. Edward Deming’s Fourteen Points. There’s a bit of self-promotion on this page, but the overall…

Cartoon: Some good predictive analytics software

*Cartoon

Year 2019

Data science

Purchased from CartoonStock.com for this blog site only. Do not reproduce this cartoon without their permission.

A Framework for Program Evaluation

*Recommendation

Year 2019

Quality improvement

This page offers a broad and comprehensive overview of how to plan and conduct a program evaluation. There are tons of resources (a mix of html pages and PDF documents)…

Quality Improvement in Healthcare

*Recommendation

Year 2019

Quality improvement

This is a slick video that outlines the quality improvement process using clever drawings. It is only 11 minutes long but provides a very nice overview.

Checklist to Evaluate the Quality of Questions

*Recommendation

Year 2019

Survey design

A detailed and comprehensive list of things to look for when you are reviewing a new questionnaire. It is based on a document QAS-99 that was originally developed by the…

SMART Objectives

*Recommendation

Year 2019

Quality improvement

The acronym SMART is a nice way to define an objective in a quality improvement. It has to be Specific, Measurable, Achievable, Relevant, and Time-Bound. This page outlines…

8 Waste Types of DOWNTIME

*Recommendation

Year 2019

Quality improvement

This page reviews the commonly used acronym DOWNTIME that classifies the eight ways that waste can occur in a manufacturing process.

NOVA, A Hole in the Sky

*Recommendation

Year 2019

Outliers

This 4 minute video talks about the discovery of the ozone hole over Antarctica and how some early indications of this hole were dismissed as outliers.

Another short biography

*Blog post

Year 2019

Professional details

I am contributing a chapter to a book (proposed title: Randomized controlled trials in medical research – gold standard or unhealthy fixation) and the book editor wanted a…

Dr. Russell Waitman. Innovation: Breaking the Barriers on Medical Information

*Recommendation

Year 2019

Professional details

This is a short article and video of Russ Waitman. Russ is my boss at one of my three jobs, and this gives a nice introduction to the sort of work I help out with.

Finding those weird characters

*Blog post

Year 2019

Statistical computing

When you take a text file from one system and use it in a different system, some of the more “exotic” characters can change on you. An example are the “smart quotes” in…

Create Awesome HTML Table with knitr::kable and kableExtra

*Recommendation

Year 2019

R software

I use R Markdown for a lot of things, but the one thing that never seems to come out the way I like is the tables. This vignette highlights some of the ways you can…

An overview of randomization techniques

*Recommendation

Year 2019

Randomization

This is a nice overview of why you want to randomize. It also talks about block randomization and covariate adaptive randomization.

HEDIS and Performance Measurement

*Recommendation

Year 2019

Quality improvement

This is another resource that came up during a talk. HEDIS is a series of performance measures in six clinical areas that is coordinated by the NCQA.

The Learning Health Care System in America

*Recommendation

Year 2019

Quality improvement

This document was recommended at a talk I attended. I have not read it yet, but the stated goal of the document to “drive the process of discovery as a natural outgrowth of…

A Systematic Examination of the Citation of Prior Research

*Recommendation

Year 2019

Writing research papers

This was a nice study, and shows a very easy model to adapt to other research problems. The authors were concerned that many reports of randomized clinical trials (RCTs)…

The most challenging thing in the world

*Quotation

Year 2019

Human side of statistics

“The most challenging thing in the world is not to learn fancy technologies, but control your own wild heart.” Yihui Xie, as quoted in Appendix C of Authoring Books wtih R…

Bending the rules of clinical trials

*Recommendation

Year 2019

Ethics in research

Many clinical trials have restrictive entry criteria to insure homogeneity of the subject pool which increases power and allows the study to proceed with a not too…

Should you blow the whistle?

*Recommendation

Year 2019

Fraud in research

This article offers some practical advice about when, how, and whether to become a whistle blower.

Competing commitments in clinical trials

*Recommendation

Year 2019

Ethics in research

The title is a bit misleading. It does not involve financial or non-financial conflicts of interest, but rather when clinical researchers violate the rules of a clinical…

Observational studies often make clinical practice recommendations

*Recommendation

Year 2019

Observational studies

This is a nice example of mining the existing medical literature to discover trends and attitudes about research. The authors take too dim a view, in my opinion, of what…

Sample applications and more

*Recommendation

Year 2019

Grant writing

It’s hard to find good examples of well-written research grants, so this website is wonderful. It shows examples of all sorts of NIH grants (R01, R03, R15, R21, R33, R41…

Sins against science

*Recommendation

Year 2019

Fraud in research

This article discusses some of the recent research showing the prevalence of scientific misconduct, offers some explanations on why this misconduct occurs, and provides some…

Framingham Contribution to Cardiovascular Disease

*Recommendation

Year 2019

Observational studies

The Framingham Heart Study, a massive longitudinal observational study, has helped identify most of the risk factors for heart disease that we commonly accept today. This…

Think positively - what has research done for us

*Blog post

Year 2019

Research design

Teaching resources

Several years ago, I was part of panel presentation at the Joint Statistical Meetings. My talk was on how to teach Statistics from an evidence-based perspective. A question…

Quote: The combination of some data …

*Blog post

Year 2019

Being updated

“The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from some data.” John Tukey, as quoted in The…

Exploratory data analysis is an attitude

*Quotation

Year 2019

Human side of statistics

Exploratory data analysis is an attitude, a state of flexibility, a willingness to look for those things that we believe are not there, as well as the things we believe…

In a world where the price of calculation continues to decrease rapidly

*Quotation

Year 2019

Data science

“In a world where the price of calculation continues to decrease rapidly, but the price of theorem proving continues to hold steady or increase, elementary economics…

How to write a literature review

*Recommendation

Year 2019

Writing research papers

This is a nice checklist of things that you should do when you are creating a literature review.

Citing one of my web pages

*Blog post

Year 2019

Writing research papers

I got an inquiry by email asking if it was okay to cite one of my web pages. Here’s what I said, more or less.

Hints for designing effective questionnaires

*Blog post

Year 2019

Survey design

I had originally cited this resources on my survey design category page, but the link was broken, so here is the correct link. It’s a nice guide. A bit too firm in its…

Leading Questions – Yes Prime Minister

*Recommendation

Year 2019

Survey design

This short video clip is an excellent illustration of how the questions leading up to a particular question on a survey can bias the response to that survey. It comes from a…

How a Feel-Good AI Story Went Wrong in Flint

*Recommendation

Year 2019

Data science

Ethics in research

Human side of statistics

Building a great statistical model does no one any good if it doesn’t pay attention to non-statistical issues. This story talks about a machine learning model to identify…

Making women in science visible

*Recommendation

Year 2019

Ethics in research

This video was recommended by my niece, and it caught my eye for a more subtle theme, perhaps. Rachel Ignotofsky is a great believer that illustration makes difficult…

Congratulations on the Promotion. But Did Science Get a Demotion?

*Recommendation

Year 2018

Ethics in research

I am recommending this article, not because I agree with it, but because it reinforces a common theme: the struggle to get and keep funding is skewing research as much as or…

Convert PowerPoint Slides to xaringan (remark.js) Slides

*Recommendation

Year 2018

Presenting research

R software

I have been constructing most of my recent presentations to R Markdown. This includes presentations that have little or no R code in them. I like using R Markdown because…

9 Reasons Excel Users Should Consider Learning Programming

*Recommendation

Year 2018

Data management

R software

Microsoft Excel is very popular, but it has many serious limitations. This article explains what you lose out on if you rely just on Excel and what additonal capabilities…

We Have Ways To Stop Rogue Scientists. They Don’t Always Work.

*Recommendation

Year 2018

Ethics in research

This is a nice review inspired by recent controversial work of a Chinese scientist who claims to have created genetically engineered babies. It outlines approaches that we…

In UC’s battle with the world’s largest scientific publisher, the future of information is at stake

*Recommendation

Year 2018

Writing research papers

The University of California (UC) is in the midst of a difficult negotiation with Reed Elsevier, a major publisher of research journals. The dispute relates to the…

Standardized Mortality Ratio

*Recommendation

Year 2018

Epidemiology

I was at a talk where mortality rates were presented in one column and the standardized mortality ratio was presented in a different column. I was a bit confused; I could…

Make PowerPoint Presentations with R Markdown

*Recommendation

Year 2018

Presenting research

R software

This is a 42 minute presentation that covers the basics of using R Markdown to produce PowerPoint files. It touches on another couple of RStudio products: R Studio Connect…

Welcome to DASL – The Data And Story Library

*Recommendation

Year 2018

Datasets

The Data and Story Library (DASL) is a collection of small and simple data sets useful for teaching basic statistical concepts. It was originally housed at the…

Getting R to shut the heck up

*Blog post

Year 2018

R software

When you are using R Markdown to create various documents, you are often interested in displaying any informative messages that appear along the way. This is especially true…

Installing R and Python in Anaconda for Biologists

*Recommendation

Year 2018

R software

Anaconda provides an easy way to manage the installation of both R and Python. The R installation includes R Studio, if you want it. While the title of this blog entry…

Fighting SASism

*Blog post

Year 2018

R software

SAS software

I told a story today in a webinar workshop that I thought I should get down in writing for my blog. It involves a prejudice unique among statisticians called SASism.

Accessible R Markdown Documents

*Recommendation

Year 2018

R software

Teaching resources

A class covering on-line teaching has reminded me about accessibility issues. This includes accessibility for blind students who rely on screen readers. This webpage post…

Cleaning Words with R

*Recommendation

Year 2018

Incomplete page

R software

Teaching resources

In many text mining or natural language processing applications, you will have problems with words that are very similar, but which are counted separately. An example might…

1.1 Billion Taxi Rides with Spark 2.2 & 3 Raspberry Pi 3 Model Bs

*Recommendation

Year 2018

Cluster computing

Mark Litwintschik has taken a large open source data set (1.1 billion taxi rides with data storage on the order of hundreds of gigabytes) and ran some benchmark queries on a…

A top Cornell food researcher has had 13 studies retracted. That’s a lot.

*Recommendation

Year 2018

Ethics in research

This is a non-technical account of Brian Wansink, a food researcher, who has been accused of p-hacking.

Call R from SPSS

*Recommendation

Year 2018

R software

SPSS software

This is a nice, easy to follow overview of how to use bits of R code within SPSS.

What to do about claims of borderline statistical significance

*Blog post

Year 2018

Hypothesis testing

A comment about the phrase “trend towards efficiency” on the Statistical Consulting Section discussion board raised a lot of interesting commentary. The phrase refers to a…

What I did in the last twelve months

*Blog post

Year 2018

Professional details

For the yearly evaluation for my part-time position in the Department of Biomedical and Health Informatics at the University of Missouri-Kansas City, I have had to prepare a…

Making it easier to discover data sets

*Recommendation

Year 2018

Data sharing

Datasets

I heard about this from the UMKC Bioinformatics twitter feed. Google has a blog entry highlighting a new search feature they’ve developed, Dataset Search. It lets you find…

False-Positive Psychology

*Recommendation

Year 2018

Hypothesis testing

This article was recommended at a talk I attended. The full title says it all.

Complex Innovative Trial Designs Pilot Program

*Recommendation

Year 2018

Research design

The FDA is encouraging new complex trial designs that are adaptive and/or Bayesian. This page describes a program where drug companies are encouraged to propose these…

Use of Electronic Health Record Data in Clinical Investigations. Guidance for Industry

*Recommendation

Year 2018

Electronic health records

The U.S. Food and Drug Administration (FDA) is encouraging great use of electronic health record data to supplement the traditional randomized clinical trials. But you need…

Next-generation phenotyping of electronic health records

*Recommendation

Year 2018

Electronic health records

This article was recommended at a talk I attended. The thesis is that we need to look at the electronic health record from the bottom up.

Super Pi, a group to teach cluster computing using the Raspberry Pi

*Blog post

Year 2018

Cluster computing

If you want to learn cluster computing and you didn’t have easy access, you had two choices. You could simulate a cluster computer on your laptop, or you could buy time in…

The five safes, designing data access for research

*Recommendation

Year 2018

Data sharing

This is a nice overview of the various dimensions of security that you need to consider when making research data available on the Internet.

JupyterLab is Ready for Users

*Recommendation

Year 2018

Integrated development environment

Jupyter is an integrated development environment that uses a notebook interface. It was originally developed for Python, but is now available for a variety of other…

lavaan tutorial

*Recommendation

Year 2018

Structural equations modelining

I have not run too many Structural Equation Modeling (SEM), so I can’t comment too much about this resource, but anytime I see something like SEM features added to R, I have…

Leaflet - an open source Javascript library for mobile-friendly interactive maps

*Recommendation

Year 2018

Geocoding

Graphical display

I have not tried this package but it was independently recommended by two separate sources that I have a lot of respect for. It uses a minimal computer interface to produce…

Python bindings for MPI

*Blog post

Year 2018

Cluster computing

The Python Software Foundation supports PyPA, the Python Packaging Authority, a group that maintains an easy to use infrastructure for distributing Python software packages.…

Python, Raspberry Pi, and cluster computing

*Blog post

Year 2018

Cluster computing

I’ve been experimenting with connecting a small number of Raspberry Pi in a cluster computer, and a good place to start is MPI (Message Passing Interface). Unfortunately…

Cluster Hat 2.0

*Recommendation

Year 2018

Cluster computing

I am working on creating a cluster computer using three Raspberry Pis. Once I get that working, I might see what I can do with the smaller model, the Raspberry Pi Zero. If I…

MPI Tutorial Introduction

*Recommendation

Year 2018

Cluster computing

MPI (Message Passing Interface) is the grandfather of all parallel programming systems. It is a series of routines that you can call from FORTRAN or C++ programs, and was…

r2d3: R Interface to D3 Visualizations

*Recommendation

Year 2018

Graphical display

R software

There’s an interesting visualization system called d3 that I only became aware of a few months ago. It uses a fairly minimal system, javascript and support vector graphics…

What day is it in my R program?

*Blog post

Year 2018

R software

There are three different ways to find out inside your R program what day it is. Let’s quickly look at each.

Business essentials for starting an independent consulting practice

*Blog post

Year 2018

Human side of statistics

Professional details

I’m giving a talk on Wednesday, August 22, titled “Business essentials for starting an independent consulting practice.” Here are a few details about this talk.

How to Clone Your Raspberry Pi SD Cards With Windows

*Recommendation

Year 2018

Raspberry Pi

I’m building a cluster of Raspberry Pi computers to run Hadoop and one of the tasks that I need is to make working backups of the micro SD cards that these computers use to…

NOOBS – Raspberry Pi documentation

*Recommendation

Year 2018

Raspberry Pi

You have several ways of installing the Raspbian operating system for the Raspberry Pi computers, but the simplest is to use NOOBS (New Out Of Box Software). This page shows…

The Dark Side of Data Science

*Blog post

Year 2018

Data science

Human side of statistics

I’m planning to give a talk on “The Dark Side of Data Science” and I’m hoping to get some interesting references and articles from my colleagues. Here is a first draft of my…

Practical deep learning for coders

*Recommendation

Year 2018

Data science

This is a MOOC (Massive Open Online Course) covering deep learning models. I have not taken it, but it comes highly recommended by others. It uses Python as the underlying…

GloVe word vector embeddings

*Recommendation

Year 2018

Data science

Text mining

When you are working with text mining, you might want to reduce the dimensionality of your problem. The word2vec algorithm, developed by Tomas Mikolov and others at Google…

A simple structure for documentation

*Blog post

Year 2018

Statistical computing

Teaching resources

Everybody has different standards for documentation, - and if you are already using a standard you like, don’t let me stop you. But if you’ve never used much documentation…

Use of Electronic Health Record Data in Clinical Investigations

*Recommendation

Year 2018

Data management

This press releases announces a “Guidance for Industry” document that the U.S. Food and Drug Administration provides from time to time on technical issues. This document…

A Review of Published Analyses of Case-Cohort Studies and Recommendations for Future Reporting

*Recommendation

Year 2018

Research design

I got a question about how to analyze a case cohort study in Stata. The person was following the code in a Stata conference presentation but was unsure about some of the…

Grading rubric for computer assignments

*Blog post

Year 2018

Statistical computing

Teaching resources

I’ve been teaching a variety of classes that require students to run a statistical analysis in a package like SAS or R and report the results. There is a tremendous variety…

How to be more effective in your professional life

*Blog post

Year 2018

Human side of statistics

This article starts with a nice anecdote about how you can be hurt by being dismissive about what someone else is saying. It also provides a nice structure, POWER, for…

How much missingness can you tolerate?

*Blog post

Year 2018

Missing data

I got a question about how much missing data could you have in a study and still feel comfortable with your data analysis. It’s a question with no hard and fast answer, but…

Bayesian meta-analysis of two proportions in random control trials

*Recommendation

Year 2018

Bayesian statistics

Systematic overviews

I got a question about Bayesian meta-analysis and found this nice teaching example. I’m not sure if the graphs are from the R package bayesmeta, but it looks like it.

Section 508 CoP: PDF Accessibility – Part One

*Blog post

Year 2018

Teaching resources

I have been somewhat lax in making my work accessible for people with disabilities. This video covers some of the basic things you can do with a PDF file to insure that it…

Microsoft is creating an oracle for catching biased AI algorithms

*Recommendation

Year 2018

Data science

Artificial Intelligence (AI) algorithms that are used for crime detection, loan approvals, and employee evaluations are considered by many to be objective, but they can…

What goes into a contract for a consultation

*Blog post

Year 2018

Human side of statistics

Someone asked me about what sort of contract to use with a new client. This person did not need a very detailed contract, but said that a handshake would not suffice. Here’s…

Big data groups at UMKC and UM/Columbia

*Blog post

Year 2018

Data science

I was at a meeting where I learned about some recent efforts with big data at the University of Missouri-Kansas City and the University of Missouri/Columbia. Here’s a brief…

Applied Survival Analysis

*Recommendation

Year 2018

Survival analysis

Although the title says “Applied”, this book has a fair amount of mathematics in it, which helps you understand why certain approaches work well. The sample outputs for this…

Analysis of Pretest-Postest Designs

*Recommendation

Year 2018

Longitudinal data

A very nice resource that talks about difference scores, relative change models, analysis of covariance, and repeated measures models.

Interval censored data analysis

*Recommendation

Year 2018

R software

Survival analysis

Michael Fay gave a short course on interval censored data at the 2010 useR! meeting. The slides from this short course provide a nice overview of the complexities of this…

Interval regression - R data analysis examples

*Recommendation

Year 2018

R software

Survival analysis

This page shows R code to handle the tricky data sets where the response is known to be inside some interval.

Adjusted survival curves

*Recommendation

Year 2018

R software

Survival analysis

This is a nice overview of how to use R to adjust survival curves in an observational study. It covers weighting and modeling with covariates and criticizes several…

What are we doing to justify all that time we’re budgeting?

*Blog post

Year 2018

Human side of statistics

An email discussion about the appropriate percentage effort on research grants has produced a lot of interesting discussions. One person raised an interesting question. The…

beepr: easily play notification sounds on any platform

*Recommendation

Year 2018

R software

This package was mentioned at the most recent meeting of the Kansas City R Users Group and was too cute not to mention.

Some interesting quality improvement resources

*Blog post

Year 2018

Quality improvement

I attended a conference on quality and patient safety, and some of the speakers mentioned some interesting resources. I googled them and saved the links here.

Reproducible research with Stata

*Recommendation

Year 2018

Reproducible research

Stata software

This outlines a way to produce “beautiful Beamer presentations” using Stata. This is a step towards the goal of reproducible research.

Draft policy on statistical support for research

*Blog post

Year 2018

Grant writing

I am drafting up a policy on statistical support for research at my part-time job at UMKC. It is loosely based on standards at the University of California, Davis and Kansas…

Learning more about SAS

*Blog post

Year 2018

SAS software

I had three students who successfully completed the Introduction to SAS class that I am teaching at UMKC. Here is the advice that I offered about how to continue to learn…

Dogs vs cats. Create an algorithm to distinguish dogs from cats

*Recommendation

Year 2018

Datasets

This is a classic data set for testing out image analysis. You have a data set of 25,000 images which are labelled dogs or cats. This is easy for a human to do, but can you…

A crummy drop-down menu appeared to kill dozens of mothers in Texas.

*Recommendation

Year 2018

Data management

This article talks about how bad the maternal mortality rates are in the United States and how bad our effort to try to quantify the rate is.

SMS Spam Collection Data Set

*Recommendation

Year 2018

Datasets

If you are interested in text mining, this is a good data set to start with. It is a bunch of text messages, each one line long, that have been classified by a human as…

Definitions of Criteria and Considerations for Research Project Grant Critiques

*Blog post

Year 2018

Grant writing

I have to help write NIH grants from time to time, and I need to always keep front and center the criteria that NIH peer reviewers use when they evaluate grants. They look…

Exploits of a Mom

*Recommendation

Year 2018

SQL

This xkcd cartoon by Scott Munro is open source, so I can hotlink the image directly. But if you go to the source, https://xkcd.com/327/, be sure to hover over the image for…

Data Sharing Network (SHRINE)

*Recommendation

Year 2018

Informatics

I’m ginvg a talk about i2b2 (among other things) and when browsing through their website, I cam across an interesting project, SHRINE. This is an acronym for Shared health…

ISO 8601

*Recommendation

Year 2018

Data management

This xkcd cartoon by Scott Munro is open source, so I can hotlink the image directly. But if you go to the source, https://xkcd.com/1179/, be sure to hover over the image…

TinyTeX: A lightweight, cross-platform, portable, and easy-to-maintain LaTeX distribution based on TeX Live

*Recommendation

Year 2018

R software

Reproducible research

Writing research papers

I’ve been using a version of LaTeX (MikTeX) for a couple of years, and it’s not bad. But when I heard about Yihui Xie’s R package, tinytex, I jumped at the opportunity to…

Guidelines for estimating biostatistician effort and resources on grants

*Blog post

Year 2018

Grant writing

What percentage effort is reasonable for Biostatistics support on a research grant? The UC Davis Biostatistics Group says 10% as a bare minimum, 35-60% for straightforward…

Statistical and Machine Learning forecasting methods: Concerns and ways forward

*Blog post

Year 2018

Data science

At first glance, you might think that this article looks like a vindication of traditional statistics. Classical time series models (methods that were available in the…

The Reinhart-Rogoff error – or how not to Excel at economics

*Recommendation

Year 2018

Data management

There has been a lot written about how lousy Microsoft Excel (and other spreadsheet products) are at data management, but the warning sinks in so much more effectively when…

EuSpRIG horror stories.

*Recommendation

Year 2018

Data management

There has been a lot written about data management problems with using spreadsheets, and there is a group the European Spreadsheet Risks Interest Group that has documented…

Developing an interdisciplinary research program

*Blog post

Year 2018

Professional details

I’ve been applying for a variety of jobs, and one of them asked for a statement on how I would develop an interdisciplinary research program. It’s fun to write these, and I…

My research interests

*Blog post

Year 2018

Professional details

I’ve been applying for a variety of jobs, and one of them asked for a statement on my research interests. I tried to emphasize the collaborative nature of my research.…

My research interests, one page limit

*Blog post

Year 2018

Professional details

Another place asked for my research interests and asked me to keep it to a single page. Gack! I do not have an easy time keeping withing page limits. Here’s what I wrote. It…

My teaching interests, one page limit

*Blog post

Year 2018

Professional details

I have been applying to a variety of jobs, and some of them, mostly universities, want a statement of teaching philosophy, research interests, or some combination. I enjoy…

My teaching approach

*Blog post

Year 2018

Professional details

I am applying for a variety of jobs and some of the universities that I am applying to want to know my approach to teaching. It’s an interesting thing to write about…

Pmean: My teaching and research statement

*Blog post

Year 2018

Professional details

I am applying to a variety of jobs and some of them ask for a statement about teaching or research. Here’s something I wrote where the employer asked for a combination of…

To combat physician burnout and improve care, fix the electronic health record

*Blog post

Year 2018

Informatics

This article is a nice counterbalance to all the glowing reports about how moving to the electronic health record is going to revolutionize health care. This effort…

Evaluation Methods in Biomedical Informatics

*Recommendation

Year 2018

Informatics

When I was talking about using the electronic health record as a measurement tool for quality improvement studies, a colleague recommended that I look at a book, Evaluation…

Starting a heron-i2b2-analytics repository

*Blog post

Year 2018

Informatics

I am working on a CTSA grant to develop repeatable downstream pipelines that directly access i2b2 and CDM. In order to promote this work and encourage others to participate…

Recommended format for homework assignments

*Blog post

Year 2018

R software

SAS software

SPSS software

I’m teaching a couple of classes, Introduction to R and Introduction to SAS, and I’m finding that students will turn in homework a variety of different ways. I’m fine with…

And the least important variable is

*Blog post

Year 2018

Human side of statistics

Linear regression

I heard a story a long time ago, and I don’t remember who told it to me and I’m probably getting all the details wrong, but I wanted to try to recreate the story from memory…

Using the transpose procedure in SAS

*Blog post

Year 2018

SAS software

A couple of my students are having difficulty with restructuring data sets in SAS. This is not surprising. Restructuring is very important, but not so easy. I decided to run…

Good Publication Practice for Communicating Company-Sponsored Medical Research: GPP3

*Recommendation

Year 2018

Writing research papers

Very little of my research fits into the category of company-sponsored medical research, but it is important to be aware of the special concerns and the extra oversight that…

Next stop - BMC Medical Informatics and Decision Making

*Blog post

Year 2018

Informatics

Professional details

I’m working part-time on a research grant and I want to publish some of the work I’ve done on this grant. The title of the paper tentatively is “Validating elastic net…

Two articles published in the Encyclopedia of Big Data

*Blog post

Year 2018

Data science

Professional details

I don’t call myself a “big data” analyst, but when a call went out seeking authors for various topics for the Encyclopedia of Big Data, I volunteered to write two articles.…

Textbook Examples Applied Survival Analysis

*Recommendation

Year 2018

R software

SAS software

SPSS software

Stata software

Survival analysis

Teaching resources

I’m teaching an online workshop for The Analysis Factor on survival analysis. It’s not announced yet, and I have a LOT of work to do before it is ready. One thing that will…

They want a short biography from me

*Blog post

Year 2018

Professional details

I should have titled this page “I’m a Star!” because the School of Medicine’s Marketing and Communications Office is asking me questions to prepare a short biography to…

Welcome to developerWorks

*Recommendation

Year 2018

Data science

Teaching resources

I got this recommendation from a friend. IBM has a large number of free resources explaining things like cloud computing and blockchain. I’m most interested in their section…

Tests of equivalence and non-inferiority

*Blog post

Year 2018

Hypothesis testing

I’m making a webinar presentation in April for The Analysis Factor. I’ve done this several times in the past. The talk in April will be on tests of equivalence and…

Exporting a graph in SAS

*Blog post

Year 2018

SAS software

I got a question about how to export a graph in SAS to a program like PowerPoint. There are several ways to do this, and I explained that you can right click on any graph…

Getting Started with the SAS 9.4 Output Delivery System

*Recommendation

Year 2018

SAS software

I don’t use SAS that much anymore. Not because it’s a bad program. Mostly it’s because it’s hard to keep on top of too many statistical packages all at once. But I’m…

Mining the electronic health record, why and how

*Blog post

Year 2018

Informatics

I’m submitting a talk to an upcoming research conference. I’m not sure if they’ll accept it, but wish me luck. Here’s the title and abstract.

Peer grading in Introduction to R, SPSS, SAS

*Blog post

Year 2018

R software

SAS software

SPSS software

I’ve gotten some helpful feedback that I need to encourage more interactions among students in the on-line classes, Introduction to R, Introduction to SPSS, and Introduction…

Changes to the Introduction to R, SAS, and SPSS classes

*Blog post

Year 2018

R software

SAS software

SPSS software

I have helped develop and have taught (along with other faculty in our department) three one credit hour pass/fail classes: Introduction to R, Introduction to SPSS, and…

Is vaccine effectiveness (VE) different from vaccine efficacy

*Recommendation

Year 2018

Critical appraisal

This is a non-technical discussion of the difference between effectiveness and efficacy (two easily confused terms) in the context of vaccination. Short answer: efficacy is…

A sampling of outstanding women in analytics

*Recommendation

Year 2018

Important statisticians

This is a list (with single paragraph descriptions) of 186 women who have accomplished great things in the area of Analytics. There is a brief accompanying article at the…

Mixed up variable names in SAS

*Blog post

Year 2018

SAS software

Some of my students in the Introduction to SAS class were having trouble reading in a tab-delimited text file, and it’s not too surprising, because some of the student in…

Data dictionaries

*Recommendation

Year 2018

Data management

This is a nice explanation of what goes into a data dictionary, written from the perspective of research data management.

The history of Hadoop

*Recommendation

Year 2018

Statistical computing

If you want to understand big data, you need to understand Hadoop. Hadoop is the technology underlying many big data efforts. But most of the descriptions of Hadoop are…

Adherence to Methodological Standards in Research Using the National Inpatient Sample

*Recommendation

Year 2018

Datasets

I normally don’t recommend articles that are stuck behind pay walls, but this is an important article. It shows how 85% of a sample of research studies using the National…

Cleaning Words with R: Stemming, Lemmatization & Replacing with More Common Synonym

*Recommendation

Year 2018

R software

Text mining

In many text mining or natural language processing applications, you will have problems with words that are very similar, but which are counted separately. An example might…

Sentiment analysis of A Christmas Carol

*Blog post

Year 2018

Text mining

I was at an interesting talk about sentiment analysis and decided to try something simple myself. Sentiment analysis is a text analytics method that compares text data with…

Reading text data into SAS

*Blog post

Year 2018

SAS software

Some of my students in my Introduction to SAS class are having trouble with a particular data set. Here are some screen shots showing how SAS can read this file in several…

Quote: Without data

*Quotation

Year 2018

Quality improvement

“Without data, you’re just another person with an opinion.” W. Edwards Deming. As quoted at https://www.goodreads.com/author/quotes/310261.W_Edwards_Deming.

An introduction to implementation science for the non-specialist

*Recommendation

Year 2018

Critical appraisal

I’ve done a lot of work with Evidence-Based Health, but one big and largely unsolved problem is how to get health care professionals to change their practices once the…

Do you need to name your function arguments in R?

*Blog post

Year 2018

R software

If you program anything in R, you’ll end up calling a lot of functions. You pass your data or your constants to these functions, and you can do it in one of two ways. You…

The Survey Statistician newsletter

*Recommendation

Year 2018

Survey design

The International Association of Survey Statisticians publishes a newsletter every six months that covers general information about surveys, announcements about meetings…

Possible webinars on consulting

*Blog post

Year 2018

Human side of statistics

Professional details

I’ve gotten an inquiry about teaching a couple of webinars. Nothing’s official yet, but let me outline the? these webinars here on my blog. If the offer becomes official, I…

My work on a CTSA grant

*Blog post

Year 2018

Data science

R software

SQL

I’m on a Clincal and Translational Science Award (CTSA) research grant (5UL1TR000001-05, formerly 1U54RR031295-01A1), which is pretty cool. My name is even mentioned a few…

Hi - I’m Mike Bostock.

*Recommendation

Year 2018

Graphical display

Important statisticians

This is an AMA (Ask Me Anything) session with Mike Bostock, a former graphics editor for the New York Times and creator of the d3.js data visualization package. I’ll be…

How to be more effective in your professional life

*Recommendation

Year 2018

Human side of statistics

This post has been combined with a similar post written on 2020-08-06.

Charging by the hour versus charging by the project

*Blog post

Year 2018

Human side of statistics

I was talking about pricing models for consulting in an email exchange and I thought I’d extract some of those comments for this blog. When you are an independent…

Syllabus for Introduction to R, Spring 2018

*Blog post

Year 2018

R software

I am teaching a class, Introduction to R (MEDB 5505). Here is the syllabus for Spring Semester 2018.

Syllabus, Introduction to SAS, Spring 2018

*Blog post

Year 2018

SAS software

I am teaching a class, Introduction to SAS (MEDB 5507). Here is the syllabus for Spring Semester 2018.

SAS University. It’s SAS and it’s free

*Blog post

Year 2018

SAS software

I am teaching a class, Introduction to SAS, that I helped design, but one where another faculty member did all the heavy lifting. I used to teach SAS classes, and I even…

The Origins of ‘Big Data’

*Recommendation

Year 2018

Data science

I’m not a big fan of the term “big data” but I’ve been applying for a couple of jobs that ask for expertise in big data instead of expertise in Statistics. So in one of the…

Philosophy News Network: Postmodernism Special Report

*Recommendation

Year 2018

Critical appraisal

I generally shy away from Philosophical debates, but I did discuss a Postmodern critique of Evidence Based Medicine a while back. When one of my more intellectual friends…

Recommendation: Philosophy News Network: Postmodernism Special Report

*Recommendation

Year 2018

Critical appraisal

I generally shy away from Philosophical debates, but I did discuss a Postmodern critique of Evidence Based Medicine a while back. When one of my more intellectual friends…

Another big data publication

*Blog post

Year 2017

Professional details

I dislike the term “big data” because it implies a class of problems that are immune from normal statistical considerations. I will admit that certain concepts such as the…

My research interests in 450 characters or less.

*Blog post

Year 2017

Professional details

I am currently looking for a full-time position. I have been part-time since 2008, because of child care issues. That will change in July 2018 when my wife retires. She’s…

My grade point averages

*Blog post

Year 2017

Professional details

In applying for various jobs, one of them wanted to know my grade point averages from school. That was over 35 years ago, but okay. I had to calculate them by hand and I…

Designing and conducting semi-structured interviews for research

*Recommendation

Year 2017

Qualitative research

This is a very helpful guide on collecting qualitative data through a semi-structured interview. It emphasizes the need for probe questions and on behaviors that you should…

No more rainbows

*Blog post

Year 2017

Graphical display

This is a nice article explaining why using a rainbow (red-orange-yellow-green-blue-indigo-violet) is a bad idea. The colors produce an artefactual banding pattern, they do…

Network analysis in cross-sectional data using R

*Recommendation

Year 2017

Network analysis

These are the slides for a very nice webinar presented by Eiko Fried. Dr. Fried provided a wealth of resources during his webinar (some of these are behind pay walls).

How to use social media in your career

*Recommendation

Year 2017

Human side of statistics

This is a short overview of five major social media sites: LinkedIn, Twitter, Facebook, Instagram, and Snapchat and how you might use them to promote your career. The…

January talk at KU

*Blog post

Year 2017

Professional details

Networking is important, and until recently I have failed to build bridges with some of the very smart people working at the University of Kansas in Lawrence. But I will be…

Can A.I. be taught to explain itself

*Recommendation

Year 2017

Data science

This is a nice article in the popular press that talks about some of the problems with “black box” models (in particular deep neural nets) used extensively in many big data…

Losing track of your transformed variables in R

*Blog post

Year 2017

R software

I got an interesting question from one of my students, and it illustrates a subtle issue that may confuse beginning R programmers. The student was trying to compute a ratio…

Resources for R

*Blog post

Year 2017

R software

Teaching resources

I attended several talks about R at the Joint Statistics meetings and noted some interesting packages and other resources during these talks. I lost track of that list until…

Beanumber repository

*Recommendation

Year 2017

Data science

R software

SQL

Teaching resources

This is the github repository of Ben Baumer. He is one of the co-authors of “Modern Data Science with R” and the data and code from that book is available here. He also…

Databases using R

*Recommendation

Year 2017

R software

SQL

This is a page outlining several related efforts at RStudio to make it easier for you to work with data stored in various relational databases.

Teaching precursors to data science in introductory and second courses in statistics

*Recommendation

Year 2017

Data science

Teaching resources

This paper talks about how to get students to think about large databases in an introductory class that normally uses “toy” problems with a few dozen rows of data.

Intro to SQL for Data Science

*Recommendation

Year 2017

SQL

Teaching resources

This is a series of videos and homework exercises that you can work on at your own pace. I have only viewed the outline for this, but anything from DataCamp comes highly…

Writing about numbers

*Blog post

Year 2017

Numbers

This is a chapter in a classic book, Medical Uses of Statistics. The writer of this particular chapter was a giant in Statistics, Frederick Mosteller. This chapter talks…

When the revolution came for Amy Cuddy

*Recommendation

Year 2017

Critical appraisal

Human side of statistics

This is one of the best articles I have ever read in the popular press about the complexities of the research process.

The unthinking approach to borderline p-values

*Blog post

Year 2017

Hypothesis testing

Writing research papers

I ran across a nice discussion of how to write the results section of a research paper, but it has one comment about the phrase “trend towards significance” that I had to…

Get credit for your data – BMC Research Notes launches data notes

*Recommendation

Year 2017

Datasets

Writing research papers

This is a new effort to get data out into the open for others to use. A data note can be on data that was not published or it could be an addendum describing data used in…

100 interview questions? A big oops on the very first one.

*Blog post

Year 2017

Statistical theory

I shouldn’t do this, because we’ve all made mistakes, especially me. But I took a peek at a website with the intriguing title “100+ commonly asked data science interview…

Search for unpublished data by systematic reviewers: an audit

*Recommendation

Year 2017

Publication bias

The authors looked at all systematic reviews (excluding methodological reviews) published in a few key journals as well as a random sample of Cochrane reviews to see how…

What does large mean when talking about negative values?

*Blog post

Year 2017

Diagnostic testing

Human side of statistics

Dear Professor Mean, I saw a paper where the authors said that they wanted a diagnostic test with a large negative likelihood ratio, because it was important to rule out a…

OpenRefine: A free, open source, powerful tool for working with messy data

*Recommendation

Year 2017

Data management

I have not had a chance to use this, but it comes highly recommended. OpenRefine is a program that uses a graphical user interface to clean up messy data, but it saves all…

How to increase value and reduce waste when research priorities are set

*Recommendation

Year 2017

Research design

This is the first in a series of articles on reducing waste in research. It focuses on funding agencies and recommends that funders should support more work on making…

Randomized Controlled Trials in Health Insurance Systems

*Recommendation

Year 2017

Randomization

Research design

While researchers often use data from health insurance systems to conduct observational studies, the authors of this research paper point out that you can also conduct…

Announcing a new monthly feature: What’s going on in this graph

*Recommendation

Year 2017

Graphical display

Teaching resources

Through the effort of a team of statisticians with the American Statistical Association, the New York Times is producing a new resource for educators called “What’s Going On…

Notice of Revised NIH Definition of Clinical Trial

*Recommendation

Year 2017

Research design

The NIH recently updated their definition of what a clinical trial is. Here is the link to the new definition. Also worth reviewing are an FAQ list, some case studies, some…

Trump’s Android and iPhone tweets - one year later

*Recommendation

Year 2017

R software

Text mining

This is a nice example of using R for text mining of twitter feeds - and the author gives lots of links and hints on how you could do something similar.

Good enough practices in scientific computing

*Recommendation

Year 2017

Data management

Writing research papers

There is more than one way to approach a data analysis and some of the ways lead to easier modifications and updates and help make your work more reproducible. This paper…

Syllabus for Introduction to R, Fall semester 2017

*Blog post

Year 2017

R software

I am teaching a class, Introduction to R (MEDB 5505). Here is the syllabus for Fall Semester 2017.

Open source as a budgetary measure

*Blog post

Year 2017

R software

Writing research papers

Like a lot of public universities, UMKC is having a lot of financial difficulty. They are asking for advice from faculty members on how to address this budget shortfall. Not…

Syllabus for Introduction to SPSS, Fall semester 2017

*Blog post

Year 2017

SPSS software

I am teaching a class, Introduction to SPSS (MEDB 5506). Here is the syllabus for Fall Semester 2017.

A quick summary of my research

*Blog post

Year 2017

Professional details

I might be giving a very brief (5 minute) overview of my research for students in the Department of Biomedical and Health Informatics. Here are some details of that work…

Dryad Digital Repository

*Recommendation

Year 2017

Data sharing

Datasets

I’ve been looking for something like this for a while. It is a repository for data sets associated with peer-reveiwed publicattions. I have only glanced at it briefly, but…

Conferences for learning R

*Blog post

Year 2017

R software

I heard about a new series of conferences for learning about R. I have not attended any of them, but they look interesting.

What are the important packages for R

*Blog post

Year 2017

R software

I got a question from one of the students in my “Introduction to R” class asking what are the important packages for R. That’s a hard question to answer, but if I got only…

Greece’s troubling prosecution of its former chief statistician

*Recommendation

Year 2017

Human side of statistics

This is an important summary about the prosecution of a statistician, Andreas Georgiu, who was only doing his job.

Analyze Survey Data for Free

*Recommendation

Year 2017

Complex surveys

R software

I’ve not had a chance to test this code, but it looks pretty good for anyone who might want to analyze one of the dozens of large databases produced by the U.S. Government.

Is the staggeringly profitable business of scientific publishing bad for science?

*Recommendation

Year 2017

Writing research papers

I attended a talk about a decade ago on the problems with for-profit publishing of scientific research and the need to aggressively adopt the open source publication model.…

The new Enigma Public

*Recommendation

Year 2017

Datasets

This is yet another interesting source of data. This site specializes in databases prepared by the United States government.

Kaggle data

*Recommendation

Year 2017

Datasets

In contrast to the five thirty eight databases which are mostly smallish, the Kaggle data sets are, as a rule, very large. They also include a lot of text data, for natural…

Five Thirty Eight Data

*Recommendation

Year 2017

Datasets

This is a github repository of a lot of interesting data sets created by the Five Thirty Eight website. I presume there is a story associated with most of these data sets.…

ProbOnto

*Recommendation

Year 2017

Probability concepts

If you work with probability distributions a lot, you find there are multiple parameterizations (e.g., the two different forms of the exponential distribution), as well as…

It only looks like a blank

*Blog post

Year 2017

R software

I was having trouble with trailing blanks in an R program. There were some strings that looked like ” Y” and “Y” and it’s easy enough to fix this, but one of the “Y” values…

This is your machine learning system?

*Recommendation

Year 2017

Data science

This xkcd cartoon by Scott Munro is open source, so I can hotlink the image directly. But if you go to the source, https://xkcd.com/1838/, be sure to hover over the image…

Why R is Bad for You

*Recommendation

Year 2017

R software

Arguing about R versus SAS often takes on a religious fervor, so I normally hesitate to recommend articles that trash one package or the other. But this one raises an…

A p-value of .000

*Blog post

Year 2017

Ask Professor Mean

Hypothesis testing

I ran a statistical test in SPSS and got a p-value of .000. I re-ran the same data in Microsoft Excel and got a p-value of 3.9433E-9. I know from scientific notation that…

Extremely imbalanced multi-center trials

*Blog post

Year 2017

Accrual problems

Bayesian statistics

There was some recent discussion of issues with multi-center trials where one center dominates, contributing as much as 94% of all the patients. What does this do to the…

One in Five Clinical Trials for Adults with Cancer Never Finish

*Recommendation

Year 2017

Accrual problems

This is a research summary of a study that found one out of every five cancer trials that “did not finish” which actually means that they stopped early for futility, if I am…

Getting out of the free consulting trap

*Blog post

Year 2017

Human side of statistics

Someone on the Statistical Consulting Section message board asked a question about how to handle a situation where a colleague was repeatedly asking for advice. How do you…

The numbers for the Science March

*Recommendation

Year 2017

Humor

Placebos in research

I normally don’t recommend other people’s tweets, but these two from Siobhan Tompson were too funny to pass up.

ROSE: A package for binary imbalanced learning

*Recommendation

Year 2017

Data science

Logistic regression

Logistic regression and other statistical methods for predicting a binary outcome run into problems when the outcome being tested is very rare, even in data sets big enough…

How big is the stuff I’m working on

*Blog post

Year 2017

Professional details

I have been working part-time on a project for the Great Plains Collaborative (GPC) under the direction of Russ Waitman and the gentle guidance of Dan Connolly, both at…

Proving the null hypothesis in clinical trials

*Recommendation

Year 2017

Hypothesis testing

I’m attending a great short course on non-inferiority trials and the speaker provided a key reference of historical interest. This reference is the one that got the…

How Bright Promise in Cancer Testing Fell Apart

*Recommendation

Year 2017

Data science

A nice overview of the problems with shoddy research in genetics testing. It highlights the work of “forensic statistics” of Keith Baggerly and Kevin Coombes.

Genetics: Clues in the code

*Recommendation

Year 2017

Data science

If you want to understand the value of genomic medicine, you can learn a lot by reviewing the case of Nicholas Volker, one of the first success stories in this area. Here’s…

Standards and guidelines for the interpretation of sequence variants

*Recommendation

Year 2017

Data science

This article outlines a standardized way to describe genetic variants.

Blind analysis: Hide results to seek the truth

*Recommendation

Year 2017

Blinding in research

This paper advocates something I would call a triple blind, keeping the doctor, the patient, and the statistician who analyzes the data in the dark as to which treatment…

Launch a Shiny App on Your Own Server in 4 Steps

*Recommendation

Year 2017

R software

It’s very easy, apparently, to set up your own server to run Shiny apps (Shiny is a web based method for interacting with R code). If you have set up Amazon Web Services…

Obnoxious use of red text in RStudio

*Blog post

Year 2017

R software

I really enjoy using RStudio, but one thing about it drives me bats. It seems to use red text for some very innocuous error messages.

Why be an independent consultant?

*Recommendation

Year 2017

Human side of statistics

Professional details

I might as well recommend something that I wrote. This is a short article in the Amstat News, a monthly newsletter of the American Statistical Association. I talk about all…

My areas of expertise

*Blog post

Year 2017

Professional details

I was asked to list my areas of expertise for an upcoming Q&A webinar that I am helping with. Here’s the list I shared.

Will the baby walk away?

*Blog post

Year 2017

Probability concepts

I submitted a cute probability problem to the Riddler section of Nate Silver’s Five Thirty Eight web site. Here’s a cut-and-paste of the problem.

PheKB. A knowledge base for discovering phenotypes from electronic health records

*Recommendation

Year 2017

Informatics

Some of the work I am doing right now could be characterized as discovering phenotypes from electronic health records. So when one of my co-workers mentioned this database…

Medicare Claims Synthetic Public Use Files (SynPUFs)

*Blog post

Year 2017

Datasets

The Centers for Medicare & Medicaid Services (CMS) provides researchers with access to Medicare claims data, which is a wonderful resources. But you have to sign a…

Conducting Clinical Research

*Recommendation

Year 2017

Research design

This is a website associated with a very nice book on the pragmatic aspects of running a clinical trial. I came across this site because I was looking for a simple example…

Are systematic overviews reliable?

*Blog post

Year 2017

Systematic overviews

Dear Professor Mean, I’m helping a student with a piece of work and he described systematic reviews as being reliable. I’m troubled by this on a number of fronts.

Text Mining with R

*Blog post

Year 2017

Data science

R software

This is an O’Reilly book (cute animal on the cover is a rabbit) that is available online for free. It’s a great resource for someone just getting started with text mining.

Cases and cohorts and controls, oh my!

*Blog post

Year 2017

Observational studies

Some asked a question about a retrospective study where you have a control cohort matched to a case cohort so the cohorts are similar on important (potentially confounding)…

R and SQL Server 2016

*Blog post

Year 2017

R software

SQL

I have not viewed this video yet, but it comes from a good friend. There is a substantial effort at Microsoft to better integrate the R programming language and their…

i2b2 Design Document. Ontology Management (ONT) Cell

*Recommendation

Year 2017

i2b2

I’m digging into some of the complexities of i2b2, especially in the concept path that shows how a particular piece of information in the electronic health record fits into…

TSHS Resource Portal

*Recommendation

Year 2017

Datasets

Teaching resources

The Teaching of Statistics in the Health Sciences (TSHS) section of the American Statistical Association has put together a set of resources for teachers including several…

How to run your first Bayesian analysis using jags software in R

*Blog post

Year 2017

Bayesian statistics

Incomplete page

Someone wanted to know how to run a Bayesian data analysis for a two group longitudinal study. There are several ways you can do this, but I had to confess I did not have an…

Looking inside the brains of scientists

*Blog post

Year 2017

Hypothesis testing

I found an interesting research study that shows what happens inside the brains of scientists as they view statistical graphs of the type commonly used in peer-reviewed…

Statistical Issues Seen in Non-Statistics Proposals

*Recommendation

Year 2017

Grant writing

If you are writing a research grant, there are a lot of statistical issues that you need to consider. This guide, prepared by the American Statistical Association…

Guidelines for Assessment and Instruction in Statistics Education College Report 2016

*Recommendation

Year 2017

Teaching resources

As a community, we statisticians have known for a long time that we do not teach that introductory level class in Statistics as well as we should. This guideline list the…

Another example of pipes in R

*Blog post

Year 2016

R software

I am using pipes in R (the magrittr package) a lot recently. It reduces the number of errors due to nested functions, among other things. I’ve given a simple example before…

A personal biography

*Blog post

Year 2016

Personal details

I got in touch with a colleague from my days at Bowling Green State University. That was in the 1980s and my life had changed substantially since those days. While I have…

When differing versions of R packages matter

*Blog post

Year 2016

R software

When you use R, you are using a program that is constantly evolving. The user-contributed packages are also evolving as well. Normally this is not that big a deal. But…

Why secondary data analysis takes a lot longer

*Blog post

Year 2016

Human side of statistics

Observational studies

Someone posted a question noting that most of the statistical consulting projects that they worked on finished in a reasonable time frame, a few were outliers. They took a…

Defining Urban and Rural Areas in U.S. Epidemiologic Studies

*Recommendation

Year 2016

Geocoding

I’m somewhat new to geocoding. One of the first things you might be interested in, if you have geographic data, is an indicator as to whether a certain address, zip code, or…

About those awful election predictions

*Blog post

Year 2016

Probability concepts

If you were on Mars for the past few days, you may not have noticed that Donald Trump has won the election. There has been a lot of commentary lately about how badly the…

Practical advice for analysis of large, complex data sets

*Recommendation

Year 2016

Human side of statistics

This is a nice compilation of issues that you should be concerned. The examples are mostly from things that interest Google, but you will find this advice itself is useful…

A simple example of pipes in R

*Blog post

Year 2016

R software

At the Joint Statistical Meetings this year, I learned a lot about recent developments in R, and not so recent developments that I was totally clueless about. One of those…

Small group presentations using screen sharing tools

*Blog post

Year 2016

Presenting research

I received a suggestion for the Kansas City R Users Group to use screen sharing tools. I am going to experiment with this a bit. Here are two tools worth trying.

Misunderstanding autism

*Blog post

Year 2016

Ethics in research

A friend of mine posted an inspiring story published in the Washington Post. Unfortunately, it did not inspire me, but rather made me worried about how often we…

Drawing the perfect circle

*Blog post

Year 2016

Cheat sheet

R software

I have an R cheat sheet, How Big Is Your Graph, that explains how to measure the size of various features of your graph in R. This blog post illustrates how you can use some…

Rotating text in an R graph

*Blog post

Year 2016

Cheat sheet

R software

I have an R cheat sheet, How Big Is Your Graph, that explains how to measure the size of various features of your graph in R. This blog post illustrates how you can use some…

Independent consulting and the cold call

*Blog post

Year 2016

Human side of statistics

There’s been some more discussion about getting started as an independent statistical consultant. One person is ready to hang their shingle and proposes to “find a niche I…

Those darn commas in SQL

*Blog post

Year 2016

SQL

I should know better, but I made a rookie mistake with SQL that took a long time for me to fix. It’s one of those detail oriented things and if you aren’t detail oriented…

What do you hate most about independent consulting

*Blog post

Year 2016

Human side of statistics

Someone on the Statistical Consulting forum mentioned that she is going to become an independent consultant when she graduates and wanted to find out from people who are…

A Tutorial on Loops in R

*Recommendation

Year 2016

R software

Teaching resources

This is a very clear, but also very detailed explanation of the for, while, and repeat loops along with the concept of vectorization. A great resource for beginners.

Where Do You Run Your R Scripts?

*Recommendation

Year 2016

R software

SQL

I’m an experienced R programmer trying to learn a little about SQL. One of my good friends who lives totally in the database world (I call her the Teradata Queen) shared a…

Oracle Dates and Times

*Recommendation

Year 2016

Dates

SQL

I’m working with R and SQL. Some of the work uses SQLite, and some of the work uses Oracle. There are subtle differences between the two, and for that matter between any two…

What greedy means to a geek

*Blog post

Year 2016

Statistical computing

I’ve run across the term “greedy” in several work related contexts, so I thought it might be worth explaining what it means.

One small grant for me, one giant leap for Biostatisticians

*Blog post

Year 2016

Professional details

Teaching resources

I’m so busy these days that it is silly to take on anything new, but I found an opportunity for a small research grant that I might want to submit a proposal for.

Published methodological quality of randomized controlled trials does not reflect the actual quality assessed in protocols

*Recommendation

Year 2016

Systematic overviews

When evaluating a series of research articles, you often have to assess the quality of the individual papers based on the type of blinding, for example. What do you do if…

By the skin of my teeth

*Blog post

Year 2016

Professional details

I have to brag a bit. I’m working part-time at Kansas University Medical Center (along with a couple other part-time jobs) and my boss asked me two weeks ago if I was…

Turning off large blocks of an R Markdown document

*Blog post

Year 2016

R software

When you’re running a large and complicated program using R Markdown, you can use the CACHE option to save a lot of time. CACHE will notice if a program chunk has stayed the…

Diverse Perspectives on a Flipped Biostatistics Classroom

*Recommendation

Year 2016

Teaching resources

This article is a synthesis of a panel discussion at the 2014 Joint Statistical Meetings on the flipped classroom. The article discusses it solely from the perspective of…

Merging in dplyr is a lot faster

*Blog post

Year 2016

Data management

R software

At the Joint Statistics Meetings, I found out that the advantages of some of the new libraries for data manipulation (like dplyr and tidyr) go beyond just the flexibility of…

Organizing data in spreadsheets

*Recommendation

Year 2016

Data management

I have some guidance on how to organize data (written back in 1999), but these guidelines are far superior. To be honest, you should use a database for anything more than…

What I need from statisticians

*Recommendation

Year 2016

Important statisticians

This interview with Nate Silver was conducted shortly after his keynote address at the 2013 Joint Statistical Meetings. I was at those meetings, but was stuck in a class (a…

The FAIR Guiding Principles for scientific data management and stewardship

*Recommendation

Year 2016

Data sharing

I’ve always been supportive of efforts to share data. For me, it’s a bit selfish, because I want to find interesting real world examples to use in teaching and on my web…

Tibbles (Tibbles are a modern take on data frames)

*Recommendation

Year 2016

R software

I’m an old dog R programmer who tends to rely on features of R that were available 10 years ago (an eternity for computers). But it’s time for this old dog to learn new…

10 Easy Steps to a Complete Understanding of SQL

*Recommendation

Year 2016

SQL

This page outlines some of the fundamental properties of SQL programming that you need to know as you start learning SQL. For example, SQL is a declarative language, meaning…

Changing the font size in R

*Blog post

Year 2016

Presenting research

R software

This is one of those obvious things that’s not obvious when you need it most. Suppose I’m doing a demo of R for a group like our wonderful Kansas City R Users Group. I want…

Changing the font size in RStudio

*Blog post

Year 2016

Presenting research

R software

Suppose you’re giving a talk and using R Studio. You want to make the fonts a bit larger so your audience can read them. It’s easy to do, once you know where to look.

dplyr and pipes: the basics

*Recommendation

Year 2016

R software

One of the recent developments in R that I was unaware of until I attended some talks at the Joint Statistical Meetings was the use of dplyr and pipes. It’s an approach to…

Hadley Wickham, the Man Who Revolutionized R

*Recommendation

Year 2016

Important statisticians

R software

Hadley Wickham has written many popular R packages, so many that they are sometimes referred to as the “Hadleyverse.” This is a nice biography that emphasizes the impact…

Bad examples of data analysis are bad examples to use in teaching

*Blog post

Year 2016

Critical appraisal

Teaching resources

I’m on various email discussion groups and every once in a while someone sends out a request that sounds something like this.

Recommendation: The Analysis of Biological Data, 2nd Edition

*Blog post

Year 2016

Teaching resources

I have not seen this book, but it comes highly recommended by Frank Harrell, which is good enough for me.

Enrichment design studies should enhance signals of effectiveness.

*Recommendation

Year 2016

Research design

I noticed several talks at the JSM 2016 on enrichment designs. I was only very vaguely familiar with what this meant, so I did a quick Google search. I found this very nice…

The Importance of Reproducible Research in High-Throughput Biology

*Blog post

Year 2016

Data quality

Informatics

Research design

I have not viewed this video yet, but have attended a similar talk and read a similar research paper by Keith Baggerly. His general message is that large biological and…

Never consult by email if you can help it

*Blog post

Year 2016

Human side of statistics

Consulting is always a back and forth process and often you will find yourself re-working things because of communication problems. That’s okay, but keep in mind that…

Simple string substitutions

*Blog post

Incomplete page

Year 2016

R software

I had to make a rather complex string substitution for a project and I thought it would help to briefly review some simpler string substitution examples in R. You can find…

100+ Interesting Data Sets for Statistics

*Recommendation

Year 2016

Datasets

This list starts out with a data set of 216,930 previous Jeopardy questions and goes from there. Not everything suggested is easily amenable for statistical analysis, but…

Institute for Digital Research and Education - Statistical Computing

*Recommendation

Year 2016

Datasets

This is a wonderful site, but for some reason, it is difficult to find. The Institute for Digital Research and Education (IDRE) at UCLA has put together some wonderful…

So you’re thinking about a systematic overview

*Blog post

Year 2016

Research design

Systematic overviews

If you are designing a systematic overview, you should talk to a statistician early in the process. There are lots of little things that you can do to make your research…

Handling date-times in R

*Recommendation

Year 2016

Data management

R software

Dates in R, like dates in any other software package, are tricky to work with. Here’s a nice guide that will help you get started.

So you’re thinking about a pilot study

*Blog post

Year 2016

Pilot studies

Research design

If you are designing a retrospective chart review, you should talk to a statistician early in the process. There are lots of statistical issues that you must think about…

Can you recommend an introductory book on Bayesian Statistics

*Blog post

Year 2016

Bayesian statistics

Teaching resources

I got an email asking for a recommendation for an introductory book on Bayesian Statistics from someone who recently graduated from our program. It’s kind of a difficult…

Recommendation: Ten Simple Rules for Effective Statistical Practice

*Recommendation

Incomplete page

Year 2016

Human side of statistics

This article has good general advice about how to run a statistical analysis, such as Rule 1: Statistical Methods Should Enable Data to Answer Scientific Questions.

Introduction to R, Monday, August 8 through Friday, August 12, 2016

*Blog post

Year 2016

R software

I will be teaching a one semester hour class at UMKC, Introduction to R (MEDB 5505) on Monday, August 8, 2016 through Friday, August 12, 2016. It runs from 9am to noon on…

Minimum standards for a github repository

*Blog post

Year 2016

Statistical computing

Using a github repository is new to me, and I need to document some things that may be obvious to more experienced programmers. Here are, as far as I understand it, the…

Too many different prior choices for the hierarchical beta binomial model

*Blog post

Year 2016

Bayesian statistics

I’m interested in studying how Bayesian hierarchical models work and I want to start with what seems like the simplest case, the hierarchical beta-binomial model. It’s…

Understanding the lasso regression model

*Blog post

Year 2016

Linear regression

R software

I wrote a program in R Markdown that shows how the lasso regression model works. It has too many pictures to be easily ported to this blog, so I’ll share a link to a pdf file…

Pretty good work for a part-timer

*Blog post

Year 2016

Professional details

I had to provided some documentation for my supervisor on what I had done in the past year (May 2015 through April 2016). It’s a very brief summary, but it’s still pretty…

Trying to save time in R ends up costing me time

*Blog post

Year 2016

R software

Sometimes you end up trying to be so clever that you out-clever yourself. This happened to me today in R. I tried something that was supposed to save me time and it ended up…

Examining the storage format for sparse matrices in R

*Blog post

Incomplete page

Year 2016

Data science

R software

I’ve been working with sparse matrices a bit for my work with the Greater Plains Collaborative. They are a very useful way of storing matrices where most of the entries are…

A megabyte is not a million bytes

*Blog post

Year 2016

R software

Statistical computing

Sometimes you forget things. Here’s an example.

So you’re thinking about a complex survey analysis (created 2016-05-10).

*Blog post

Year 2016

Complex surveys

I’m helping someone who is looking at a secondary data analysis that involves a complex sampling schemes. This means that the survey used cluster sampling, and/or stratified…

Which R package should I use?

*Blog post

Year 2016

R software

Working with R is great in that if anything has been done in Statistics, there is an R package that will do it. The problem is that sometimes there are four packages that…

So you’re thinking about a retrospective chart review

*Blog post

Year 2016

Research design

If you are designing a retrospective chart review, you should talk to a statistician early in the process. There are lots of statistical issues that you must think about…

Bayesian computing with INLA

*Recommendation

Year 2016

Bayesian statistics

Longitudinal data

Multilevel models

R software

This page promotes a new approach to a broad class of models (spatio-temporal models, latent variable models, mixed models) using a fast approximation to the Bayesian…

Calculating 90 day readmission rates

*Blog post

Year 2016

Longitudinal data

Secondary data analysis

Someone asked me how to calculate a 90 day readmission rate from a large database. It’s a tricky problem because for many databases, it requires you to examine the data from…

Interpretation of Changes in Health-related Quality of Life: The Remarkable Universality of Half a Standard Deviation

*Blog post

Year 2016

Clinical importance

I’ve typically mocked the use of effect sizes in research, but perhaps I need to be a bit more open minded. This paper looked at the “minimally important difference” (note…

Using version control through git, github, and R Studio

*Blog post

Year 2016

Statistical computing

I’m definitely “old school” when it comes to programming, but there comes a time when even this old dog needs to learn a new trick. I decided yesterday to use version…

Some simple examples of single imputation

*Blog post

Year 2016

Missing data

I wanted to use R to show some simple approaches to imputing missing values. These approaches are difficult to support because they require that you make some questionable…

Some open source Kaplan Meier curves

*Blog post

Year 2016

Incomplete page

Survival analysis

I’m giving a talk on the Kaplan-Meier survival curve and wanted to show and interpret a few real examples from the open source literature.

Reporting and methodological quality of sample size calculations in cluster randomized trials could be improved: a review

*Recommendation

Year 2016

Multilevel models

Sample size justification

The sample size justification for a cluster randomized trial is messy. It requires the use of an intra-class correlation or something similar (the authors use the term…

The number of subjects per variable required in linear regression analyses

*Recommendation

Year 2016

Linear regression

Sample size justification

There are several rules of thumb out there about how many subjects that you need for a multiple linear regression model. Most of these rules look at the ratio of subjects…

Is my odds ratio zero or infinity?

*Blog post

Year 2016

Measuring benefit and risk

I know you told me that when one of the row probabilities in a two by two table is 0% or if one of the row probabilities is 100%, then the odds ratio is either 0 or…

The biggest statistics papers of all time

*Blog post

Year 2016

Writing research papers

I’m giving a short talk about the Kaplan-Meier curve and found out an interesting fact about the 1958 paper by Edward Kaplan and Paul Meier that introduced this curve. It…

The perils of shortening a survey

*Blog post

Year 2016

Survey design

Dear Professor Mean, I’m trying to publish a research study that involves some survey data, but the peer-reviewer is complaining about something I did. There was a scale…

Do we really need to teach all this math stuff?

*Blog post

Year 2016

Teaching resources

I got tagged in a Facebook post about an article criticizing the emphasis on math in high school and that proposes replacing some of the more theory based courses like…

My current work at the Greater Plains Collaborative

*Blog post

Year 2016

Human side of statistics

I’m spending a fair amount of time over the next few months working with Russ Waitman and the Greater Plains Collaborative (GPC). It’s an interesting job so far, and one of…

PLOS ONE 2015 Reviewer Thank You

*Blog post

Year 2016

Professional details

Writing research papers

I reviewed a paper for PLOS One in 2014 and got a nice acknowledgment, but I also reviewed a paper for the same journal in 2015. Here’s the acknowledgment for that…

The data structure in i2b2

*Blog post

Year 2016

Statistical computing

I’m working with the Greater Plains Collaborative on a research project and my work requires me to understand the underlying data structure of a system known as i2b2. It’s…

Selection of controls in case-control studies

*Recommendation

Year 2016

Observational studies

I’m working on a project where the researchers need a case-control study, though they may not know that yet. I want to show them what a case-control study gives them that…

The need for documentation standards

*Blog post

Year 2016

Statistical computing

I’m working in a team programming environment and I would have to characterize the quality of the documentation as uneven. I’m going to make the case for having detailed…

The problem with incentivizing

*Blog post

Year 2016

Grant writing

I came across a question, “How does your institution incentivize researchers to write more grants?” that was posted a while ago. I felt it was too late to respond directly…

Recent (and not so recent) advances in statistical computing

*Blog post

Year 2016

Statistical computing

I’m giving a talk to the Statistics students at the University of Central Missouri. Here’s the title and abstract of my talk.

My latest short biography

*Blog post

Year 2016

Professional details

I am giving yet another talk and wanted to take some time to update my earlier short biography.

Searching through a mess of files

*Blog post

Year 2016

Statistical computing

I am working on a project that has a series of files in R and R Markdown, and I need to track down where a particular function was originally defined. In Unix based systems…

Business essentials that you need to know before starting your career as an independent statistical consultant

*Blog post

Year 2016

Human side of statistics

I am giving a presentation on the business essentials that you need to know before you start a career in independent statistical consulting. Here is a summary of what I’ll…

Calculating power for a test of association in a two by two table

*Blog post

Year 2016

Sample size justification

A colleague was curious to see the formulas behind the power calculations done by many statistical software programs and online calculators. In particular, she wanted to see…

Simulating power for a test of association in a two by two table

*Blog post

Year 2016

Incomplete page

Sample size justification

In an earlier blog post, I slogged through the calculation of power for a test of association in a two by two table. You can also approximate power using a simulation. It is…

A rant about the reader pays model of publication

*Blog post

Year 2016

Writing research papers

Something came up in our department about a predatory pay for access journal that was soliciting support. All the appropriate warnings were made (there’s a nice explanation…

How detailed should I make my data analysis plan.

*Blog post

Year 2016

Research design

Dear Professor Mean, I could use some advice on defining and following analysis plans for research proposals. I can see how in well-trodden research, where the nuances of…

The Survey Statistician

*Recommendation

Year 2016

Survey design

The International Association of Survey Statisticians (IASS) has a twice-yearly newsletter that talks about meetings and events sponsored by the association, informal…

Information about the Great Plains Collaborative Breast Cancer Study

*Blog post

Year 2016

Professional details

I’m starting a new project as an independent consultant. Normally, I talk very little on my blog about specific projects that I work for, but this work is for a group, the…

The Coin Flip: A Fundamentally Unfair Proposition

*Recommendation

Year 2016

Randomization

A flip of a coin does not result in an exact 50-50 chance of heads or tails. It depends a lot on how the coin is flipped, of course, but there is a bias. This article…

The Empirical Evidence of Bias in Trials Measuring Treatment Differences

*Recommendation

Year 2016

Critical appraisal

Randomization

When I wrote a book about Evidence Based Medicine back in 2006, I talked about empirical evidence to support the use of certain research methodologies like blinding and…

My research interests

*Blog post

Year 2016

Professional details

I got an email from someone at UMKC with the title, Director of Undergraduate Research. She was

Two grumpy editorials at NEJM

*Blog post

Year 2016

Data sharing

Quality improvement

I don’t have time to follow the journals as closely as I should, but I was shocked to find two very nasty editorials in recent issues of the New England Journal of Medicine.…

ENCODE: Encyclopedia of DNA Elements

*Recommendation

Year 2016

Datasets

The genetics research community should be lauded for the openness with which they share research data. You can find numerous data sources that are free and without ANY…

UMKC is now offering Qualtrics software to researchers

*Blog post

Year 2016

Survey design

One of the UMKC internal publications, UMatters, had a brief article about Qualtrics. What is Qualtrics, and why is UMKC offering it to researchers?

Odds ratio with a zero in the table

*Blog post

Year 2016

Ask Professor Mean

Measuring benefit and risk

I have a data set where 94 out of 100 patients with cancer have activation of a gene, while 0 out of 50 of the controls have activation. When I compute the odds ratio, I get…

My book chapter on R

*Blog post

Year 2016

Professional details

I was asked by a colleague to write a chapter for a book he was editing, Big Data Analysis for Bioinformatics and Biomedical Discoveries. My chapter was “R for Big Data…

Lyndon B. Johnson Space Center job opening for a GS-14 Statistician

*Recommendation

Year 2016

Human side of statistics

I get a lot of emails mentioning job openings and I normally delete them unread. This one caught my eye, not because I wanted to apply for it, but because it illustrates how…

Preprints and the Ingelfinger rule

*Blog post

Year 2016

Open source

Writing research papers

The same blog that I highlighted below had a commentary about how clinicians almost never publish pre-prints of their work. This is in contrast to other fields, most notably…

A Grant Submission New Year’s Resolution

*Recommendation

Year 2016

Grant writing

Michael Lauer, the Deputy Director for Extramural Research at the United States National Institutes for Health shows some interesting statistics on when people submit grants…

Points to consider on switching between superiority and non-inferiority

*Recommendation

Year 2015

Hypothesis testing

One of the most confusing aspects of medical research is the difference between non-inferiority and superiority trials. This article explains in simple terms what the two…

The COMPare Project

*Recommendation

Year 2015

Critical appraisal

Publication bias

One of the many problems with medical publications is that researchers will choose which outcomes to report based on their statistical significance rather than their…

Differences between information in registries and articles did not influence publication acceptance

*Recommendation

Year 2015

Critical appraisal

Publication bias

Here’s a research article tackling the same problem of changing outcome measures after the data is collected. Apparently, this occurs in 66 of the 226 papers reviewed here…

The Likelihood Ratio Slide Rule poster submission

*Blog post

Year 2015

Diagnostic testing

Professional details

I submitted a poster to the 2015 UMKC Faculty Research Symposium (described at the UMKC Office of Research Support website). It’s a chance to show off some of the work I did…

A book review of my first book

*Blog post

Year 2015

Critical appraisal

Professional details

I wrote a book about nine years ago and interest in it has largely died down. Perhaps I should write a second edition. Anyway, I ran across a book review that I had not seen…

Safeguarding Patients in Clinical Trials with High Mortality Rates

*Blog post

Year 2015

Blinding in research

Early stopping

Ethics in research

This is an article the I would trot out if anyone tried to argue that a Data Safety and Monitoring Board should, like the investigators, be blinded as to treatment status…

My Google Scholar profile

*Blog post

Year 2015

Professional details

A while back, I set up a publication list in Google Scholar. It tracks the number of citations received by each article that I published. One of my articles has a massive…

Quote: That’s not an experiment

*Quotation

Year 2015

Critical appraisal

Referring to anecdotal data: “That’s not an experiment you have there, that’s an experience.” Sir Ronald A. Fisher. I do not know where I found this quote. Sorry!

Recommendation: Clinical trials: discerning hype from substance

*Recommendation

Year 2015

Randomization

I was attending a short course taught by Susanne May on clinical trials (very good, by the way) and she mentioned an interesting publication. It talks about the “random…

How many research subjects

*Blog post

Year 2015

Sample size justification

Here’s a quote from yours truly.

Nonlinear regression for the difference of two exponentials

*Blog post

Year 2015

Incomplete page

Nonlinear regression

R software

Rmarkdown graphs

I wanted to provide an overview of how you analyze a classic nonlinear regression model. It is a difference of two exponential functions. This nonlinear function is used…

How big is my graph?

*Blog post

Year 2015

Broken link

Incomplete page

R software

When you are drawing a graph in R, sometimes you have to check how big things are before you can do anything else. There are many different ways of measuring size. Here are…

PS: Power and Sample Size Calculation

*Recommendation

Year 2015

Sample size justification

Someone stopped by today with a power calculation and I asked what software they used. They showed me something I had not seen before, a program developed by the Department…

A non-technical answer to why we need Markov Chain Monte Carlo

*Blog post

Year 2015

Accrual problems

Bayesian statistics

Someone was looking for examples of illustrative examples to help explain to people without a statistical background how MCMC methods can be applied to help solve real world…

Finding interesting peer-reviewed articles that illustrate statistical tests

*Blog post

Year 2015

Teaching resources

Someone asked how do you find peer-reviewed articles that use simple statistical tests so your students can see the structure of papers that report on statistical analyses.…

Research vs Quality Improvement

*Recommendation

Year 2015

Ethics in research

I ran across a one page handout in PDF format that discussed the difference between research and quality improvement. It was written from the perspective of the IRB…

What problems does introversion cause for a statistical consultant?

*Blog post

Year 2015

Human side of statistics

Someone posed an interesting question on the Statistics Consulting message board of the American Statistical Association. To paraphrase, her question was what sort of…

My H-index

*Blog post

Year 2015

Professional details

It’s a silly number, perhaps, but I tried to calculate my H-index today. The H-index lists your publications in order from the most cited to the least cited and then finds…

R number 6 in IEEE 2015 Top Programming Languages, Rising 3 Places

*Recommendation

Year 2015

R software

This Revolutions blog talks about a fairly rigorous evaluation of popular programming languages done by the Institute of Electrical and Electronics Engineers (known by most…

The pros and cons of cluster randomized trials

*Blog post

Year 2015

Multilevel models

Research design

I’m helping out a researcher with sample size justification for a cluster randomized trial. I may write a bit about that soon, but in the process of double checking my…

I want to learn (learn more) about R

*Blog post

Year 2015

R software

Teaching resources

I get a lot of questions along the lines of “I want to learn R, can you help me?” or “Where can I learn more about R?” or some other variation. These questions are usually…

Files for my R class

*Blog post

Year 2015

Being updated

Here is a brief abstract.

How do you select variables for a risk adjusted model?

*Blog post

Year 2015

Risk adjustment

I was helping a colleague write a response to a reviewer who asked about a risk adjusted model. How did you select the variables for adjustment? He/she speculated that we…

Some interesting publicly available data sets

*Blog post

Year 2015

Datasets

I’ve been looking for a few interesting data sets for use as teaching examples. I wanted data associated with peer-reviewed publications. It’s a difficult and tedious…

This is Statistics promotional toolkit

*Blog post

Year 2015

Human side of statistics

The American Statistical Association is promoting careers in statistics though a new campaign titled “This is Statistics”. They just added some very nice promotional…

My research contributions to Evidence Based Medicine

*Blog post

Year 2015

Professional details

The U.S. National Institutes of Health (NIH) has a new biosketch format where they ask you to summarize “up to five of your most significant contributions to science.”…

My research contributions to patient accrual models

*Blog post

Year 2015

Professional details

The U.S. National Institutes of Health (NIH) has a new biosketch format where they ask you to summarize “up to five of your most significant contributions to science.”…

Informed consent in a study without human subjects

*Blog post

Year 2015

Ethics in research

Do you need an informed consent form if you are not conducting research on human subjects?

A short biography for the person introducing me

*Blog post

Year 2015

Professional details

I get requests for a short biography from people asked to introduce me. I like to store these on my website so that I can refer to them and update them. Here’s the latest…

My research contributions to numerical accuracy

*Blog post

Year 2015

Professional details

The U.S. National Institutes of Health (NIH) has a new biosketch format where they ask you to summarize “up to five of your most significant contributions to science.”…

My research contributions to reproductive toxicology

*Blog post

Year 2015

Professional details

The U.S. National Institutes of Health (NIH) has a new biosketch format where they ask you to summarize “up to five of your most significant contributions to science.”…

I am now a number in the ORCID database

*Blog post

Year 2015

Professional details

Life in the world of research is complicated, but it gets worse when you have a relatively common last name like “Simon.” There are thousands of research publications…

Developing Grant Proposals: Guidelines for Statisticians Collaborating Under Limited Resources

*Blog post

Year 2015

Grant writing

This article provides guidance for developing the “statistical considerations” section of a research grant. I normally do not use that term, and suggest separate sections on…

PLOS ONE 2014 Reviewer Thank You

*Recommendation

Year 2015

Writing research papers

I don’t do nearly enough peer reviewing, in part because it is a thankless, anonymous task. But one journal editor sent me a nice email pointing out that my name was listed…

Can I replace missing values with zero?

*Blog post

Year 2015

Missing data

I have a large data set from a household budget survey with 20,000 records. When I calculate the mean for some of the variables, there are some missing values. Sometimes it…

Validating a test of diabetes

*Blog post

Year 2015

Diagnostic testing

Sample size justification

I have a simple algorithm that determines whether a person is diabetic or not. I am planning on validating this algorithm, and I need to know how many patients I need to…

Training on how to write a grant

*Blog post

Year 2015

Grant writing

I usually do not recommend commercial products, as I know most of you have very limited funds. But when it comes to grants, you should consider paying for good training. The…

What not to say in the limitations and alternative strategies section of your grant

*Blog post

Year 2015

Grant writing

I was reviewing a grant and the section on limitations and alternative strategies started off with the following sentence, “We do not anticipate any major limitations in…

Improving Bioscience Research Reporting: The ARRIVE Guidelines for Reporting Animal Research

*Recommendation

Year 2015

Critical appraisal

A lot of people have adapted and updated the CONSORT Guidelines to reporting clinical trials to handle other types of research. One of these adaptations is the ARRIVE…

Beyond Bar and Line Graphs: Time for a New Data Presentation Paradigm

*Recommendation

Year 2015

Graphical display

Many scientists rely on bar graphs and line graphs that effectively reduce your data to a single mean per group. Even with the addition of error bars, the whole process…

An Introduction to Social Media for Scientists

*Recommendation

Year 2015

Human side of statistics

It’s easy to mock social media, but these are important tools not just for sharing pictures of the food your eating but for informing your colleagues about your research.…

Restoring invisible and abandoned trials

*Blog post

Year 2015

Publication bias

Too much research data goes unreported, leading to a serious distortion of the evidence base that clinicians need to make intelligent medical decisions. The authors of this…

Equations using MathType

*Blog post

Year 2015

Presenting research

Obsolete page

NOte: This page is obsolete. I am currently using Markdown, MathJax, and TeX to generate equations.

Examining relationships in R

*Blog post

Year 2015

R software

Rmarkdown graphs

I’m giving a talk for the Kansas City R Users Group on how to get a preliminary impression of relationships between pairs of variables. Here is the R code and output that I…

Acceptable response rates

*Blog post

Year 2015

Observational studies

Survey design

I review a lot of observational studies in the literature, and I am concerned about the response rates and when they fall so low that they tend to produce problems with…

Nonparametric tests for multifactor designs

*Blog post

Year 2015

Logistic regression

Nonparametric tests

I want to run nonparametric tests like the Kruskal-Wallis test and the Friedman test for a setting where there may be more than one factor. Everything I’ve seen for these…

Forget confounding, and think of things in terms of covariate imbalance

*Blog post

Year 2015

Risk adjustment

Someone noted in a passing comment in their email that they found the term “confounding” to be difficult and confusing. I’ve been doing this stuff for over thirty years, but…

Editorial (Basic and Applied Social Psychology)

*Recommendation

Year 2015

Bayesian statistics

Hypothesis testing

Recommended does not always mean that I agree with what’s written. In this case. It means that this is something that is important to read because it offers an important…

Rich Data, Poor Data

*Recommendation

Year 2015

Statistical models

Nate Silver emphasizes an important point about when statistical models can really shine: when there is a rich source of data and lots of opportunities to test the…

Missing values in R talk

*Blog post

Year 2015

R software

I’m talking a bit about missing values in R this afternoon for the Kansas City R Users Group. Here is what I’ll be talking about.

New R Package: cdcfluview

*Recommendation

Year 2015

R software

I work a lot with secondary datasets and I’m always looking for new and interesting resources. There is a CDC site that tracks flu reports and with a bit of effort, you can…

P-Values

*Recommendation

Year 2015

Hypothesis testing

Randall Munroe, author of the xkcd comic strip, will often comment on Statistics. This cartoon shows how p-values are typically interpreted.

The answer is 17 years, what is the question. Understanding time lags in translational research

*Blog post

Year 2015

Critical appraisal

A widely quoted statistic is that it takes 17 years for research to find it’s way from the initial discovery to clinical practice. That statistic has always bothered me. How…

Tessera. Open source environment for deep analysis of large complex data

*Recommendation

Year 2015

Data science

R software

I have not had time to preview this software, but it looks very interesting. It takes large problems and converts them to a form for parallel processing not by changing the…

Analyzing ordinal salary categories

*Blog post

Year 2015

Logistic regression

Ordinal data

I have three variables: physicians (%), dentists (%), and salary categories. I want to know if there is a difference in the percentage of physicians and dentists in each…

Transparent reporting of a multivariable prediction model for individual prognosis or diagnosis (TRIPOD): the TRIPOD Statement

*Recommendation

Year 2015

Writing research papers

If you are writing up a paper that uses a complex regression model (complex meaning multiple independent variables), you need to document information that allows the reader…

Report on Survey Participation Refusals

*Blog post

Year 2014

Exclusions in research

The American Association for Public Opinion Research (AAPOR) convened a task force to address the increasing tendency of people to refuse to respond (as is their right) to a…

Meta-analysis of ordinal data

*Blog post

Year 2014

Systematic overviews

Dear Professor Mean, I would like to conduct a meta-analysis of several studies. The data in these studies were evaluated using an ordinal scoring system coded as 0,1,2,3.…

In search of justification for the unpredictability paradox

*Recommendation

Year 2014

Critical appraisal

Randomization

Systematic overviews

This is a commentary on a 2011 Cochrane Review that found substantial differences between studies that were adequately randomized and those that were not adequately…

Requiring fuel gauges. A pitch for justifying impact evaluation sample size assumptions

*Recommendation

Year 2014

Grant writing

Sample size justification

This blog entry from the International Initiative for Impact Evaluation talks about the deficiency in many research proposals sent to that organization. They rely too much…

What Teachers Should Know about the Bootstrap: Resampling in the Undergraduate Statistics Curriculum

*Recommendation

Year 2014

Bootstrap

Tim Hesterberg has been a long time advocate of the use of the bootstrap. In this article, he provides a nice general overview of the bootstrap with examples of how it works…

I need a clinical research coordinator

*Blog post

2014

Human side of statistics

Dear Professor Mean, I run a clinic and have a company interested in having my patients participate in a clinical trial. They tell me that I need to have a clinical research…

Cox regression in R

*Blog post

Year 2014

R software

Survival analysis

I wanted to show a couple of Cox proportional hazards regression models in R for a talk I am giving for the R users group.

More Kaplan-Meier curves in R

*Blog post

Year 2014

R software

Survival analysis

I found a larger data set and wanted to show how you could use the Kaplan Meier curves as a preliminary screen of some categorical and continuous variables in a larger and…

Kaplan-Meier curves in R

*Blog post

Year 2014

R software

Survival analysis

I am giving a talk about using R for survival analysis and I wanted to talk first about the Kaplan-Meier curve and how you might draw it in R.

Communicating Statistical Findings to Consulting Clients Operating in a Decisionmaking Climate: Best and Worst Practices

*Recommendation

Year 2014

Human side of statistics

There were a large number of excellent talks at the 2014 Joint Statistics Meeting. This session discusses practical issues associated with communication. Although I did not…

Sample size of 12 per group rule of thumb for a pilot study

*Blog post

Year 2014

Pilot studies

Sample size justification

This study is (sadly) not available for free on the Internet - but it is still worth highlighting here. Steven Julious provides some justification for the use of twelve…

What is the probability of a probability of one

*Blog post

Year 2014

Bayesian statistics

Someone wrote asking me about a variation of the “Rule of Three”. This rule says that if you observe zero events out of n, an upper 95% confidence limit for n is…

An example of a simple sample size justification

*Blog post

Year 2014

Sample size justification

Someone asked me for a sample size justification for a study involving a historical control group of 30 patients and a treatment group of unspecified size. I thought it…

A brief abstract of my research interests

*Blog post

Year 2014

Grant writing

I attended a working group meeting for researchers interested in Chem bio Defense applications. They asked each attendee to write a brief abstract of their research…

Special issue–Using Big Data to Transform Care

*Recommendation

Year 2014

Data science

Ethics in research

The July 2014 issue of Health Affairs is devoted entirely to “big data”.<U+00A0> The articles provide a general overview to big data - several applications of big data - big…

Simple longitudinal data sets to illustrate data management

*Blog post

Year 2014

Datasets

Longitudinal data

Missing data

I am working on a class that will teach basic data management and graphics using the R programming language with parallel classes in SPSS and SAS. On the third or fourth day…

Software on my computer

*Blog post

Year 2014

Obsolete page

Professional details

This page is obsolete. I am keeping because I have fun looking back at things I did many years ago.

Adapt the personal statement on your biosketch to the specific grant

*Blog post

Year 2014

Grant writing

When you are asked to prepare a biosketch for a research grant, you should adapt the personal statement of the biosketch to highlight the specific skills that you have that…

Who is your authorized official?

*Blog post

Year 2014

Broken link

Grant writing

This page is obsolete. I am keeping it around for nostalgic reasons.

A biased sample of car speeds

*Blog post

Year 2014

Survey design

Dear Professor Mean, I read a newspaper report about speed limits and how few people obeyed them. A reporter decided to collect some hard data and drove exactly at the speed…

MLPowSim software

*Recommendation

Year 2014

Longitudinal data

Sample size justification

This site provides description of a free software package - MLPowSim, that calculates power for complex random effects models. It was developed by the Centre for Multilevel…

Sample size for a study of reproducibility

*Blog post

Year 2014

Measuring agreement

Sample size justification

Dear Professor Mean: I am using a risk stratification tool for patients presenting to the ED with chest pain. This has been a well validated tool in the ED, but I want to…

Comparisons within randomised groups can be very misleading

*Recommendation

Year 2014

Longitudinal data

In studies with a baseline, examining the decline exclusively within the treated group, or examining the decline in the treated group and then separately examining the…

What should go into a data codebook

*Blog post

Year 2014

Data management

Before you start your data entry, you should create a data codebook. If you don’t have a data codebook when you hand your data over to someone else, take the time to create…

History of SPSS

*Blog post

Year 2014

Statistical computing

I’m helping to put together three separate classes, Basic data management and analysis with R [SAS / SPSS]. As part of these classes, I need to discuss the history of these…

FDA: R OK for drug trials

*Recommendation

Year 2014

R software

This blog post reviews a presentation by Jae Brodowsky, a statistician with the U.S. Food and Drug Administration that put to bed the rumor that FDA will only accept…

History of R

*Blog post

Year 2014

R software

I’m helping to put together three separate classes, Basic data management and analysis with R, SAS, SPSS. As part of these classes, I need to discuss the history of these…

History of SAS

*Blog post

Year 2014

SAS software

Statistical computing

I’m helping to put together three separate classes, Basic data management and analysis with R [SAS / SPSS]. As part of these classes, I need to discuss the history of these…

Course proposal on setting up an independent consulting practice

*Blog post

Year 2014

Human side of statistics

I was asked to prepare a proposal on a short course about consulting for an upcoming Statistics conference. I had talked about this in an earlier blog post. Here is the…

A review of methods for missing data

*Recommendation

Year 2014

Missing data

This is a nice summary of the advantages and disadvantages of various methods for handling missing values.

Meet John Gawalt, Director of the National Center for Science and Engineering Statistics

*Recommendation

Year 2014

Important statisticians

This is a brief interview with John Gawalt, the new director of the National Center for Science and Engineering Statistics within the National Science Foundation.

8 tips for doing data visualization right.

*Recommendation

Year 2014

Graphical display

This slide show includes some examples of really bad (and a few really good) graphics with some explanations of general principles for data display.

Using BUGS within the R programming environment

*Blog post

Year 2014

Bayesian statistics

R software

I am giving a talk today for the Kansas City R Users group about BUGS (Bayes Using Gibbs Sampler). I have already written extensively about BUGS and the interface to BUGS…

Data doesn’t speak for itself

*Recommendation

Year 2014

Graphical display

Presenting research

This blog post explains that you can’t just put a graph up on a screen and immediately expect people to understand it. You need to provide critical context to help your…

Not all scientific studies are created equal

*Blog post

Year 2014

Observational studies

This video gives a non-technical overview of the strengths and weaknesses of observational studies.

Proposed outline for How to Start and Run an Independent Statistical Consulting Business

*Blog post

Year 2014

Human side of statistics

There has been a bit of discussion on submitting a proposal to teach a class on running an independent consulting business for an upcoming statistics conference. I think it…

Pmean: The IRB questions my sample size calculation

*Blog post

Year 2014

Sample size justification

I got a question today from someone submitting a research protocol to the Institutional Review Board (IRB). The IRB had some concerns about the power calculation. In…

The random risks of randomised trials

*Recommendation

Year 2014

Randomization

This is an overview of some of the ethical controversies associated with randomization. It includes an interesting story of an early trial by Archie Cochrane that raised a…

Stretching an already borderline sample size

*Blog post

Year 2014

Sample size justification

I was working with a client who had a limited population of medical residents to choose from, and it would be a struggle to get even 60 of them. The primary outcome was…

Two data sets illustrating the analysis of continuous variables

*Blog post

Year 2014

Datasets

I am looking for good teaching examples that will illustrate methods for univariate and bivariate analysis of continuous variables. Here are two publicly available data sets…

Using statistical design principles to plan a Monte Carlo analysis – part 2

*Blog post

Year 2014

Statistical computing

I’ve been working more on a Monte Carlo study of various Bayesian estimators and it makes me think about certain principles that we statisticians use in experimental design…

Post hoc sample size calculations

*Blog post

Year 2014

Post hoc power

Someone asked about references on post hoc power calculation on the MEDSTATS email discussion group and, as we all know, this is a very bad idea. But someone offered a…

More on Big Data Training for the Scientific Workforce

*Recommendation

Year 2014

Data science

The United States National Institutes for Health is very interested in big data and has developed a working group, Big Data to Knowledge (BD2K). This blog post from Sally…

Predicting clinical trial results based on announcements of interim analyses

*Blog post

Year 2014

Early stopping

If you’ve ever been involved with interim reviews of clinical trials on a DSMB (Data Safety and Monitoring Board), you will be warned about the importance of…

Quote: Excel’s graphics can be great. The problem occurs

*Quotation

Year 2014

Graphical display

…when people assume that the Excel output is enough. I think of all the research papers in economics where the authors must have spent dozens of hours trying all sorts of…

Estimating the efficiency of a completely randomized block design

*Blog post

Year 2014

Analysis of variance

I needed to look up a formula for the estimating the relative efficiency to a completely randomized block design to a design without blocking.

Using statistical design principles to plan a Monte Carlo analysis

*Blog post

Year 2014

Statistical computing

I want to run a Monte Carlo analysis of various Bayesian estimators to see how they perform when the prior distribution is “wrong”. I’m like everyone else–I just plunge in…

Comparing two vectors with possible missing values

*Blog post

Year 2014

R software

I want to compare two vectors in R that have the same length and identify where, if anywhere, that the two vectors don’t match. It sounds like an easy thing to do, but…

foreach: Foreach looping construct for R

*Blog post

Year 2014

R software

This is an add-on package for R that allows you to separate a lengthy programming task into different pieces, each of which can run on a separate core of your multi-core…

Meet Charles J. Rothwell, Director, National Center for Health Statistics

*Recommendation

Year 2014

Important statisticians

This is a brief interview with the director of the National Center for Health Statistics, a statistical agency for the United States government that produces many nationally…

Qualifications for Teaching an Introductory Statistics Course

*Recommendation

Year 2014

Teaching resources

The American Statistical Association and the Mathematical Association of America published a joint statement on the qualifications that a college teacher would need in order…

plotrix: Various plotting functions

*Recommendation

Year 2014

Graphical display

R software

R has a lot of nice plotting features built in - but this add-on package adds some more - especially the ability to designate a break in one of your axes.

A guide to the line style arguments for R graphics

*Recommendation

Year 2014

Graphical display

R software

Melissa Clarkson created a very nice two page PDF file that shows very clearly the sometimes subtle difference in how various line style arguments work in R. Highly…

NIH is interested in big data

*Blog post

Year 2014

Data science

The National Institutes of Health has shown a recent interest in “big data.” You can define big data in several ways, but a common characteristic is the three V’s. Big data…

How many months should you wait before re-testing?

*Blog post

Year 2014

Research design

I got a question that I had never heard before, and it sort of is a statistics question and sort of isn’t. A researcher was comparing two methods of training residents in a…

Why Coincidences, Miracles And Rare Events Happen Every Day.

*Blog post

Year 2014

Probability concepts

This is an interview with David Hand, the author of a new book, The Improbability Principle: Why Coincidences, Miracles and Rare Events Happen Every Day. The discussion…

Summary of my research interest in patient accrual in clinical trials.

*Blog post

Year 2014

Accrual problems

My boss at UMKC (I’m part-time at UMKC and part-time independent statistical consultant) asked me for one of those “summarize the research you’ve been working on” so she…

Why randomized controlled trials fail but needn’t: 2. Failure to employ physiological statistics, or the only formula a clinician-trialist is ever likely to need (or understand!)

*Recommendation

Year 2014

Sample size justification

This is a classic article about the relationship between signal, noise, sample size, and confidence. It provided pragmatic guidance on designing a trial to make the best use…

Quote: Because statistics has too often been presented

*Quotation

Year 2014

Teaching resources

Because statistics has too often been presented as a bag of specialized computational tools, with morbid emphasis on calculation, it is no wonder that survivors of such…

Troubleshooting Public Data Archiving: Suggestions to Increase Participation

*Recommendation

Year 2014

Ethics in research

I’ve always been a big fan of data sharing, mostly for selfish reasons. I like to see interesting data sets and use them as teaching examples and on my website. There are…

Will 2015 be the Beginning of the End for SAS and SPSS?

*Blog post

Year 2014

SAS software

R software

This is a provocative title but the actual blog post itself is far more nuanced. By several measures, R is becoming more and more popular, but that hardly means that SAS or…

Savage Chickens cartoon on optimistic graphs

*Recommendation

Year 2014

Graphical display

I checked the licensing rules before posting this. Thank you, Doug Savage, at savagechickens. A direct link to this cartoon is here.

Calculating statistics that have limitations

*Blog post

Year 2014

Hypothesis testing

Someone asked what you should do if you get a request to compute a p-value on a post hoc analysis. In general, any statistic computed on a post hoc analysis is likely to be…

The Next Billionaire: A Statistician Who Changed Medicine.

*Recommendation

Year 2014

Important statisticians

This is a nice profile of Dennis Gillings, a statistician who started a small company in the 1980s with only 5 employees. This company, Quintiles, is now the world’s largest…

No power calculation for a Phase II trial

*Blog post

Year 2014

Sample size justification

There was an discussion on the message board for the Statistical Consulting Section of the American Statistical Association started by a question about a Phase II trial. The…

The dget function in R is very slow

*Blog post

Year 2014

R software

I made another rookie mistake in R. I have a program in R that needed to store a large matrix for later re-use. You can use the dput function to put a copy of the matrix out…

I have turned off the comments feature on all pages

*Blog post

Year 2014

Website details

This page is obsolete (it refers to a version of my website developed under WordPress). I am keeping it around for sentimental reasons.

Large randomized controlled trials are ready for retirement

*Recommendation

Year 2014

Randomization

Dean Ornish contributes his response to a series of invited essays on the topic “What Scientific Idea is Ready for Retirement?” His choice is the large randomized controlled…

Survey of Attitudes Toward Statistics (SATS)

*Recommendation

Year 2014

Survey design

In an earlier post, I had recommended the Statistics Attitude Survey. There is a very similar survey available, The Survey of Attitudes Toward Statistics (SATS), created by…

Resources for a workshop in R

*Blog post

Year 2014

Broken link

Obsolete page

R software

This page is obsolete but I am keeping it around for nostalgic reasons.

Statistics Attitude Survey scale

*Recommendation

Year 2014

Survey design

Dennis Roberts has a webpage with several attitude scales that have been published in the peer-reviewed literature. The fifth one on the list is a Statistics Attitude Scale…

Git can facilitate greater reproducibility and increased transparency in science

*Recommendation

Year 2014

Statistical computing

This article talks about git, a version control system for computer programmers, and how it can be used by researchers to improve the ability of others to understand and to…

What I like about R

*Blog post

Year 2014

R software

I’m helping out with a beginner’s R workshop and I might say a few words at the beginning about what I like about R. There are three big things, really.

What’s so good about early anyway.

*Recommendation

Year 2014

Diagnostic testing

This blog entry notes how easy it is to fool yourself into thinking that a screening program is doing well because it finds problems “early while you still have a chance.”…

Recommendation: A Quick Guide for Developing Effective Bioinformatics Programming Skills

*Recommendation

Year 2014

Informatics

R software

So you want to be a bioinformatitian? I can barely pronounce the word myself. But it’s a growing field with lots of interesting opportunities. This paper explains some of…

Resolutions for this blog for 2014

*Blog post

Year 2014

Website details

I took a couple of weeks off from everything work related, including this blog. I’m back today. My goal in 2014 is to try to post about 6 entries per week on this blog, with…

Some simple examples of manipulating the axes in a graph

*Blog post

Year 2014

Data visualization

Rmarkdown graphs

I want to start with a simple artificial example, a cubic function. With this simple function, you will see different ways of displaying information on the x and y axes.

The qqplot

*Blog post

Year 2014

Checking assumptions

Linear regression

R software

Rmarkdown graphs

Many statistical procedures are based on the assumption that your data has a normal distribution. The normal probability plot is a useful graphical tool for asessing this…

Comparison of Logistic Regression versus Propensity Score When the Number of Events Is Low and There Are Multiple Confounders

*Recommendation

Year 2013

Risk adjustment

Propensity scores represent an intriguing alternative method to reduce the impact of confounding variables, especially when there are multiple potential confounding…

Sample size for comparing two diagnostic tests

*Blog post

Year 2013

Sample size justification

I had a client come in with a sample size question. It involved the comparison of two diagnostic tests to a gold standard. There a couple of different ways to attack the…

DataMind website

*Recommendation

Year 2013

R software

DataMind is a website offering free tutorials for the R programming language and tools that let you develop your own tutorials based on R Markdown. I have not tested any of…

Study Development (Kansas City area resource)

*Recommendation

Year 2013

Grant writing

This is an excellent local resource for those of you in the Kansas City area. They have guidance on coming up with a study idea, finding funding, and identifying study…

Claims lacking specificity are meaningless

*Blog post

Year 2013

Critical appraisal

I recently encountered a claim about the unlimited applications for a new statistical model. I, for one, tend to view “unlimited applications” as a negative comment rather…

Use equal sign for assignmentin R?

*Recommendation

Year 2013

R software

I learned R back when the only way to assign a value was with the <- operator. For example, if you were computing the hypotenuse of a triangle, you’d use c <- sqrt(a^2+b^2).…

Is Possibility Theory better than Probability Theory?

*Blog post

Year 2013

Bayesian statistics

Someone on a LinkedIn group posted a question about “Possibility Theory.” The question itself had a lot of hype, claiming that “time has expired for Probability Theory.”…

Simple example of Fourier transform

*Blog post

Year 2013

Being updated

This page is a bit confusing. The link to the earlier version uses the name wavelet.html, but the text shows a simple Fourier transform. Is there also a simple example of…

Any other comments? Open questions on questionnaires. A bane or a bonus to research?

*Recommendation

Year 2013

Survey design

This is a classic reference that is worth re-posting. No one seems to know what to do about those pesky open-ended questions you see on a survey. This article offers…

The cost of a bad prediction

*Blog post

Year 2013

Bayesian statistics

Paul Krugman wrote up an interesting application of Bayes Theorem on his blog on the New York Times. I want to adapt his example and expand it a bit.

How confidence intervals become confusion intervals.

*Recommendation

Year 2013

Confidence intervals

The desire among researchers for a black and white dichotomy between “significant” and “not significant” results leads to a lot of unnecessary confusion.

The riddle of experience vs. memory

*Recommendation

Year 2013

Human side of statistics

There are a series of experiments that show that your memory of an event is colored more by the experience at the end of the event. This leads to some fascinating…

Five Fridays in a month

*Blog post

Year 2013

Being updated

Earlier versions are here and here.

You can now register for an account on my blog.

*Blog post

Year 2013

Obsolete page

This post is obsolete, but I am keeping it around for nostalgic reasons.

Row over breast cancer screening shows that scientists bring some subjectivity into their work.

*Recommendation

Year 2013

Systematic overviews

This is a classic reference that reminds us that even with all the objective methods developed for systematic overviews, there is still a core of choices that are largely…

Two questions you should always ask at the end of a consulting session

*Blog post

Year 2013

Human side of statistics

There was a discussion in the ASA Consulting Section forum about how to avoid “failures” in consulting. Failures can mean a variety of things, missed deadlines, incorrect…

Revised standards for statistical evidence

*Recommendation

Year 2013

Bayesian statistics

This article compares the Bayesian standard of what constitutes convincing evidence to the frequentist reliance on the p-value to measure evidence. The author concludes that…

Blog is up and ready for testing

*Blog post

Year 2013

Obsolete page

This post is obsolete, but I decided to keep it around for nostalgic reasons.

Twenty tips for interpreting scientific claims

*Recommendation

Year 2013

Critical appraisal

This article provides advice to non-statisticians on how to interpret claims made in the peer-reviewed literature.

Testing an R function

*Blog post

Year 2013

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Hedging your bets on an informative prior

*Blog post

Year 2013

Being updated

Earlier versions are here and here.

Can I focus on a subset of conditions in my experiment

*Blog post

Year 2013

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Running JAGS from R, a simple example

*Blog post

Year 2013

Being updated

Earlier versions are here and here.

Confusion about BUGS

*Blog post

Year 2013

Broken link

Bayesian statistics

R software

Note 2024-05-28: This page notes some of the problems with obsolescence of software, but some of the links that document the obsolescence are themselves obsolete. You may…

Developing a computer program using modern methods

*Blog post

Year 2013

Being updated

Earlier versions are here and here.

I get a letter published in the Kansas City Star

*Blog post

Year 2013

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Resource for statisticians called as legal experts in a trial

*Blog post

Year 2013

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Data sources for a proposed course on secondary data analysis

*Blog post

Year 2013

Teaching resources

I am giving a talk at the Joint Statistical Meetings (JSM) in Toronto. I’m still tweaking the slides just a few hours before the talk. The title is “Data sources for a…

Sample chapter: The first three steps in a descriptive data analysis

*Blog post

Year 2013

Being updated

buttonology (uncountable)

Calculating predicted probabilities from a logistic regression model

*Blog post

Year 2013

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

R code for estimating the duration of a clinical trial with a fixed sample size

*Blog post

Year 2013

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

R code for estimating the sample size of a clinical trial with a fixed duration

*Blog post

Year 2013

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

R code for estimating the sample size of a clinical trial with a fixed duration

*Blog post

Year 2013

Accrual problems

Bayesian statistics

Please note that I have not had a chance to test the code on this updated page.

How do you compute an adjusted probability?

*Blog post

Year 2013

Being updated

Earlier versions are here and here.

The confidence interval for my odds ratio is too narrow!

*Blog post

Year 2013

Being updated

Earlier versions are here and here.

Deciphering a non-linear curve

*Blog post

Year 2013

Being updated

You can find an earlier version of this page on my website.

Counting squares

*Blog post

Year 2013

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A complex subgroup definition

*Blog post

Year 2013

SPSS software

I got a question about a complex definition of a subgroup for data in SPSS. I’ve changed a few details, but the gist of the question goes like this:

Placing the mind of a statistician into software

*Blog post

Year 2013

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What does it really mean to say that a mean of a large number of variables is approximately normal

*Blog post

Year 2013

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Elbow model for accrual

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Elbow model for accrual

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Mixture of two binomial distributions

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What you should look for in a statistical consultant

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A single wildly large value makes you less confident that the mean of your data is large

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Animations in R

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Analyzing data from the National Hospital Ambulatory Care Survey

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Data sharing

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Lasso talk

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Lasso talk, figure 1

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Lasso talk, figure 2

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Lasso talk, figure 3

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Lasso talk, figure 4

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Lasso talk, figure 5

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Lasso talk, figure 6

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Mapping my runs in R

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Are you qualified to make that comment?

*Blog post

Year 2012

Being updated

Earlier versions are here and here.

Don’t write your own questionnaire

*Blog post

Year 2012

Being updated

Someone asked for general guidance on how to write your own questionnaire. I wrote a rather negative response.

Debating the validity of snowball sampling

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Borderline p-values

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

When should I use the Fisher’s Exact Test and when should I use the Chi-Square Test

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What’s the name of the test for comparing two proportions?

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Data management in R versus SAS

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Whiskers in a boxplot

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Parsing information in an XML file

*Blog post

Year 2012

Being updated

Note: This page was written before I knew about the stringr package in R. It simplifies the code and makes it easier to understand. If I find the time, I would like to…

The secret to great wealth is …

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Counting pages at my old and new websites

*Blog post

Year 2012

Obsolete page

This page is obsolete, but I am keeping it around, mostly for nostalgic reasons.

New post

*Blog post

Year 2012

Being updated

Here is a brief abstract.

An interesting mistake I made in BUGS

*Blog post

Year 2012

Being updated

I am just learning how to run BUGS software. I’ve used WinBUGS, which is a stand-alone program for Windows, and OpenBUGS, which is an Open Source version that runs on…

Reviewing how the binomial and negative binomial distributions work

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A simple example of change of variable

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A fishy story about randomization

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Statistical distributions borrowed from Wikipedia

*Blog post

Year 2012

Being updated

Earlier versions are here and here.

Accrual with refusals, exclusions, or dropouts

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

The simple accrual model, redefined

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

BUGS model for the simple Poisson accrual model

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Fitting the homogenous accrual model in BUGS

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Deriving accrual using the geometric distribution

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Bad scaling choices for the SPSS ROC curve

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Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What’s new

*Blog post

Year 2012

Being updated

I’ve made a lot of updates to my website. Here are some of the recent highlights:

Iowa talk on accrual

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Those pesky tab characters

*Blog post

Year 2012

Data management

SPSS software

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Free consultation means no co-authorship?

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Why use a Bayesian adaptive trial?

*Blog post

Year 2012

Bayesian statistics

The Bayesian adaptive trial controls the probability of randomizing a patient to each of the proposed dose groups. As data emerges during the study, the probabilities are…

Making predictions based on just the correlation

*Blog post

Year 2012

Being updated

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How sample size calculations are reported in the literature

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What non-statistical skills do consultants need?

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Questions for a panel on statistical consulting

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Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Percentage of care that does not have a medical basis

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Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Promoting your consulting career in the era of web 2.0

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Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Honorable mention for my R code on accrual

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Arguing with the material in an ethics training program

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What to report when SPSS says the p-value is zero

*Blog post

Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Is sample size justification really different for animal studies compared to human studies?

*Blog post

Year 2012

Ask Professor Mean

Sample size justification

Dear Professor Mean, I’ve spent my entire career (so far) in developing statistical analysis plans for human subjects research. Recently, a neuroscientist who performs…

Post hoc power persists because peer-reviewers demand it

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Year 2012

Being updated

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A very silly graph

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Year 2012

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Author pays model

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Year 2011

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Some thoughts on a backup policy

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Year 2011

Being updated

Earlier versions are here and here.

Definition of translational research

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Year 2011

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Review of new James Penston book

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Year 2011

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Strange results in KMeans clustering

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Year 2011

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Unrealistic scenarios for sample size calculations

*Blog post

Year 2011

Sample size justification

I’m not a doctor, so when someone presents information to me about the clinically important difference (a crucial component of any sample size justification), I should just…

Discrepancies in the chisquare test

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Year 2011

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Example abstracts for a training class

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Year 2011

Critical appraisal

Teaching resources

I am giving a webinar to a group that is interested in applications of statistics to Alzheimer’s disease and schizophrenia. I wanted to show some real world uses of p-values…

Justifying the sample size in a qualitative research study

*Blog post

Year 2011

Qualitative research

Sample size justification

I was asked to help justify the sample size for a qualitative research study. When the goals of a study are qualitative, the sample size justification is also qualitative.

Why is a 20% dropout rate bad?

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Year 2011

Being updated

How can we give an evidence based answer about why 20% loss of follow-up in a randomized trial is too much?

Possible webcast topics for a new client

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Year 2011

Teaching resources

I was asked to develop a list of webcast topics for a client working in the pharmaceutical industry. They are listed roughly in priority order for the first half. I have…

SPSS won’t compute my odds ratio!

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Year 2011

Being updated

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Looking at another grant opportunity

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Year 2011

Being updated

It must be masochism on my part, but I’m looking at writing yet another grant. This grant would go to the Heartland Institute for Clinical and Translational Research and…

A bunch of univariate nonparametric tests versus a single parametric model

*Blog post

Year 2011

Logistic regression

I’m working on a of weight loss during hospitalization. I’m measuring the percent change in the weight loss from admission to discharge and looking at the factors that…

Meta-analysis with non-comparable procedures

*Blog post

Year 2011

Being updated

In publications on meta-analysis where vast numbers of papers must be culled from the analyzable dataset due to non-comparable procedures. The resulting smaller sample sizes…

Lasagna’s Law on patient recruitment

*Blog post

Year 2011

Accrual problems

I sent out a question to an email discussion group asking about documentation of sample size shortfalls in clinical research. Someone suggested that I google “Lasagna’s…

My entry into the Applications of R in Business Competition

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Year 2011

Being updated

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Net-accessible resources for group sequential designs

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Year 2011

Early stopping

I am trying to locate a good net-accessible resource for the group sequential designs, and sample size re-estimation for adaptive designs. Can you help?

How you can teach Bayesian methods in an introductory Statistics class and why you should

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Year 2011

Bayesian statistics

There’s been a discussion among members of the Statistics in Epidemiology Section of the American Statistical Association about what topics should be covered in an…

Conditional Frailty Models

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Year 2011

Being updated

One of the people I am working with is interested in using gap time analysis with a conditional frailty model. I was impressed with this request and asked her to send any…

Statistical literacy talk

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Year 2011

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Proposal for session on grant writing

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Year 2011

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What single idea will make the biggest impact on healthcare today

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Year 2011

Being updated

Earlier versions are here and here.

Draft grant submission on patient accrual

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Year 2011

Accrual problems

Here’s an early draft of a grant submission on patient accrual. It is in response to PA-11-180, and we would submit this by February 5, 2012. I have made comments to myself…

Sharing the same classroom for five consecutive years

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Year 2011

Being updated

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Should I report the univariate or the multivariate logistic regression analysis?

*Blog post

Year 2011

Logistic regression

I have results from four univariate logistic regression models and one multivariate logistic regression model with all four variables. In my univariate analysis, all the…

Statistics is more than just cutting computer code

*Blog post

Year 2011

Human side of statistics

Someon on LinkedIn asked how to react to a comment like “Statistics is just cutting computer code, right?” Here’s how I responded.

I can’t get SAS to model the cluster effects in the MEPS data set

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Year 2011

Complex surveys

I’m trying to use SAS to analyze data from the Medical Expenditure Panel Survey (MEPS) but when I try to model the cluster effect using proc glimmix, I get an error message.…

Can I salvage my negative confidence interval

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Year 2011

Confidence intervals

I was involved in a small case-control project that was intended to explore some genotypes as predictors of disease progression. We had between 50 and 60 cases and controls…

What are the assumptions of logistic regression

*Blog post

Year 2011

Logistic regression

Does anyone have a good reference for the assumptions of binary logistic regression? I have a client who has an anonymous reviewer who says his analysis doesn’t meet one of…

New flat rate for consulting

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Year 2011

Professional details

This page is obsolete. I am keeping it around for nostalgic reasons.

Positive statements about no conflicts of interest

*Blog post

Year 2011

Conflict of interest

There is a lot of confusion about when you can report “No conflict of interest.” You don’t know whether this means that there is no financial relationship with any…

Banning editorials and clinical reviews from authors with industry ties

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Year 2011

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

The advantages of IBM SPSS software

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Year 2011

SPSS software

You have a lot of choices for how to do your data analysis. I have found that the best option for most people I work with is to use IBM SPSS software. Here are the main…

What goes on your business card

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Year 2011

Independent consulting

Someone who was about to embark on an independent consulting career asked me what you should put on your business card. My advice was to keep it simple.

Publicity for your consulting career

*Blog post

Year 2011

Being updated

Human side of statistics

I have been talking about independent consulting a lot at the Joint Statistical Meeting, and I wanted to summarize some of my commentary about publicizing your consulting…

Using Social Media to promote your consulting career

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Year 2011

Independent consulting

I am leading a roundtable discussion of using Social Media to promote your consulting career. Here are some things that I plan to discuss.

Twelve subjects in a within subject design

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Year 2011

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Validation of OpenEpi software

*Blog post

Year 2011

Statistical computing

I was asked to “validate” a software program called OpenEpi. If you want to validate software, you need to show that it produces correct answers for a variety of test cases.…

Second invitation to talk about how independent consulting is different

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Year 2011

Independent consulting

I have a second invitation to talk on how independent consulting is different in 2012 (send me an email if you’re curious about when and where). I was asked to submit an…

There’s more than one way to calculate a Fisher’s exact p-value

*Blog post

Year 2011

Measuring benefit and risk

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Establishing accuracy for a statistical program (created 2011-07-14).

*Blog post

Year 2011

Statistical computing

I’ve been asked to establish that a particular program, OpenEpi, can accurately calculate test statistics for a two by two table. The package appears quite good, and it is…

Teaching classes for a fee

*Blog post

Year 2008

Being updated

Teaching resources

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Calculating a confidence interval for a standard deviation

*Blog post

Year 2011

Confidence intervals

Rmarkdown code

Suppose that you had a sample of 80 observations and you computed a standard deviation of those 80 observations. Like any other statistic, the standard deviation will have…

Software that I use on my computers

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Year 2011

Statistical computing

I thought it might be useful to list the software programs that I use on my various laptop computers. That way I can check to see if I have installed the programs that I…

How much work does that second reviewer have to do in a meta-analysis

*Blog post

Year 2011

Systematic overviews

Someone asked about the process of using a second reviewer in a meta-analysis to abstract data from studies. The rationale for a second reviewer, of course, is to establish…

Statistical calculators on the web

*Blog post

Year 2011

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Looking for help to test software for monitoring accrual in a clinical trial

*Blog post

Year 2011

Accrual problems

I need some collaborators for a grant I am writing from people who conduct prospective clinical trials. I am working on methods to monitor patient accrual in clinical…

Small business grant? Maybe not (created 2011-06-16).

*Blog post

Year 2011

Accrual problems

I want to document on this webpage, a general idea of where we might want to submit a grant to continue our work on accrual models. In particular, I was originally leaning…

How I became a skeptic

*Blog post

Year 2011

Critical appraisal

I’m a big fan of the skeptic movement. If you’re not familiar with this, it is a group of professional and amateur scientists who critically examine claims of fringe science…

Cartoon about placebos

*Blog post

Year 2011

Being updated

I drew a small cartoon about placebos. I know you think that this is drawn by a professional artist, but I did this. Really!

Which version of SPSS should you get

*Blog post

Year 2011

SPSS software

I was showing a client how to use their version of SPSS to a variety of different things and when I went to run a logistic regression model, it wasn’t there. Apparently…

When you’re stuck writing major sections of another person’s grant

*Blog post

Year 2011

Being updated

I was helping someone write a grant when I got that request that I always dread, “Can you write this section of the grant.” I hate those requests for a personal reason–I’d…

New shortened structure for NIH grants

*Blog post

Year 2011

Writing research grants

I am working on an NIH grant looking at various Bayesian models for accrual. NIH changed the grant proposal format last year to a much shorter proposal. Good for them, I…

It’s been a quiet year

*Blog post

Year 2011

Professional details

I was asked by my boss to document my scholarly activities for the past year. I used July 1, 2010 through June 30, 2011 as the time frame (I don’t anticipate a lot happening…

Can prisons randomly assign prisoners without their consent?

*Blog post

Year 2011

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A simple segmented linear regression model, borrowed from the BUGS manual

*Blog post

Year 2011

Bayesian statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Bayesian inference on the geometric distribution

*Blog post

Year 2011

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Using a binary coding trick illustrated by a Car Talk puzzler

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Year 2011

Data management

I often need to see how often certain variables and combinations of those variables appear in a data set. If the variable is binary, there is a trick for doing this that is…

A simple hierarchical model for the Poisson distribution, borrowed from the BUGS manual

*Blog post

Year 2011

Bayesian statistics

I am interested in various extensions to the simple Bayesian model for accrual that Byron Gajewski and I derived and published in Statistics in Medicine. An important…

Promoting your consulting career in the era of Web 2.0

*Blog post

Year 2011

Independent consulting

I was approached by a member of the planning committee for the American Statistical Association Conference on Statistical Practice about giving a talk at that conference.…

Yet another biography

*Blog post

Year 2011

Professional details

I’m asked often to provide a short biography that can be used as an introduction to a talk I am giving. Anything that I pass along to an introducer I also post on my…

What I’d look for in a new computer

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Year 2011

Statistical computing

I am hardly an expert on computing, but I do try to help out when someone asks me about what sort of computer they should buy for statistical analyses. Here are some general…

Is it ethical to provide statistical consulting on a disseration to a Ph.D. candidate

*Blog post

Year 2011

Being updated

Someone asked a hypothetical question about consulting assistance for a Ph.D. candidate. Clearly some assistance is okay and the question is when the work becomes so much…

How independent consulting is different

*Blog post

Year 2011

Being updated

I am scheduled to be part of a panel discussion titled “Successful Statistical Consulting: The Practicalities.”

The importance of being self-critical

*Blog post

Year 2011

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Why is my standard deviation so small

*Blog post

Year 2011

Descriptive statistics

I am helping someone with a projec that involves (among other things), computing averages of many Likert scale items. A Likert scale has different interpretations, but I use…

I can’t find a standard deviation for my power calculations

*Blog post

Year 2011

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Examples of the difference made by high quality research

*Blog post

Year 2011

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Can Bayesian methods help with small sample sizes?

*Blog post

Year 2011

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Resources for Comparative Effectiveness Research

*Blog post

Year 2011

Teaching resources

I attended an interesting webinar on Comparative Effectiveness Research (CER). I always try to take notes during presentations like this, but my notes are often a poor…

Thinking about the title for my second book

*Blog post

Year 2011

Professional details

As I mentioned on an earlier webpage, Cambridge University Press has agreed to publish my second book. There were some suggestions, including a change in the proposed title…

Quotes and references from Dr. Harrell

*Blog post

Year 2011

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Does a wide confidence interval mean that my conclusions are all wrong?

*Blog post

Year 2011

Confidence intervals

My confidence intervals are very wide. I do not know how to explain this. Does this mean that my results are likely to be wrong?

The nature of advice on email discussion lists

*Blog post

Year 2011

Teaching resources

I participate on several email discussion lists, and someone complained a bit about the advice he was getting. “So my question is if this forum is open for people like me?…

Macros in Stata

*Blog post

Year 2011

Stata software

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

My special Zotero style

*Blog post

Year 2011

Website details

I use Zotero to produce html code for the “Outside Resource” section of my category pages. It requires a special style which I have adapted.

I won’t serve on my IRB, but there is a way I can still help.

*Blog post

Year 2011

Ethics in research

I had offered to help out our local IRB but was not careful to clarify how I could help. This resulted in me being appointed as an alternate member of the IRB. That’s not a…

Good news about my second book proposal

*Blog post

Year 2011

Being updated

I got an email three days ago from my contact at Cambridge University Press. It looks like they want to publish my book!

Creating LaTex formulas on the fly

*Blog post

Year 2010

Being updated

Writing research papers

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Location of my UMKC office

*Blog post

Year 2010

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Using the Poisson distribution for modeling accrual

*Blog post

Year 2010

Accrual problems

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Closed form solution for homogenous accrual

*Blog post

Year 2010

Being updated

Accrual problems

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Are certain CAM therapies undeserving of further study

*Blog post

Year 2010

Being updated

Critical appraisal

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Poem to help you remember the quotient rule

*Blog post

Year 2010

Being updated

Mathematics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Transforming the parameter also transforms the prior distribution

*Blog post

Year 2010

Bayesian statistics

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

The odds ratio in logistic regression is the opposite of what it should be

*Blog post

Year 2010

Being updated

Logistic regression

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

BUGS is more than just one program

*Blog post

Year 2010

Bayesian statistics

Being updated

I am working on some Bayesian models that use a program called BUGS. BUGS stands for Bayesian Inference Using Gibbs Sampling. There are several ways you can run BUGS, and it…

Ambiguity in the definition of the exponential distribution

*Blog post

Year 2010

Being updated

Probability distributions

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The Science-Based Medicine blog defends itself

*Blog post

Year 2010

Being updated

Evidence-based medicine

I get a few fan letters from people, which are greatly appreciated, but when I get the rare critical response, I am even more grateful. It doesn’t matter if the criticism is…

Taking conflict of interest too far

*Blog post

Year 2010

Being updated

Conflict of interest

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Would you hire someone who knew theory

*Blog post

Year 2010

Being updated

Human side of statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Justifying the sample size in an equivalence study

*Blog post

Year 2010

Being updated

Sample size justification

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Work in pharma versus work in academia

*Blog post

Year 2010

Being updated

Human side of statistics

Earlier versions are here and here.

Reconciling the various ways to calculate power for an ANOVA model

*Blog post

Year 2010

Being updated

Sample size justification

I am trying to reconcile all the different ways that power can be calculated for an ANOVA model. The various formulas are confusing.

Lost page

*Blog post

Year 2010

Being updated

Multilevel models

Earlier versions are here and here.

Poster presentation at the Missouri Technology conference

*Blog post

Year 2010

Accrual problems

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

If you knew that failure was not an option what would you do

*Blog post

Year 2010

Being updated

Human side of statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Why the least squares regression line has to pass through XBAR, YBAR

*Blog post

Year 2010

Being updated

Linear regression

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Putting variable names into a model automatically

*Blog post

Year 2010

Being updated

R software

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Is there something better than Evidence Based Medicine out there

*Blog post

Year 2010

Being updated

Evidence-based medicine

Someone asked me about a claim made on an interesting blog post on the Science Based Medicine blog. The writer of this post, Kimball Atwood, claims that Science Based…

Oh those pesky interactions!

*Blog post

Year 2010

Being updated

Modeling issues

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My new twitter account

*Blog post

Year 2010

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Can you compute a confidence interval for your p-value

*Blog post

Year 2010

Being updated

Hypothesis testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Using information theory to identify discrepancies within and between text files

*Blog post

Year 2010

Being updated

Information theory

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Is it ethical to recruit a panhandler

*Blog post

Year 2010

Ethics in research

Someone asked a question about the ethics of approaching a panhandler and sharing information about a research study. I don’t know all the details, but apparently, this…

News and announcements

*Blog post

Year 2010

Obsolete page

This page is obsolete, but is being kept around anyway.

Learning how to fit latent growth curve in Amos

*Blog post

Year 2010

Being updated

Structural equations modeling

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Is Evidence-Based Medicine too rigid

*Blog post

Year 2010

Being updated

Evidence-based medicine

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What is a Generalized Estimating Equations Model

*Blog post

Year 2010

Being updated

Multilevel models

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What is principal components analysis?

*Blog post

Year 2010

Being updated

Data science

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Competing books to the book I am planning to write

*Blog post

Year 2010

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What should clients get from you at the end of your first consulting session

*Blog post

Year 2010

Being updated

Human side of statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Glossary for my second book

*Blog post

Year 2010

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What’s a fair price for SPSS?

*Blog post

Year 2010

Being updated

SPSS software

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Fighting the claim that any size difference is clinically important

*Blog post

Year 2010

Being updated

Sample size justification

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Standard operating procedures for a statistical consulting center

*Blog post

Year 2010

Being updated

Human side of statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Acknowledgments for my second book

*Blog post

Year 2010

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

When should research in a given area end?

*Blog post

Year 2010

Systematic overviews

Someone asked a rather philosophical question, is there ever an end to research in a given area? Will there ever be a “last word” on a research topic. Here’s what I wrote in…

Pooling different measures of risk in a meta-analysis

*Blog post

Year 2010

Being updated

Systematic overviews

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Sample chapter: The first three steps in selecting an appropriate sample size

*Blog post

Year 2010

Being updated

Sample size justification

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Sample chapter, the first three steps in selecting an appropriate sample size

*Blog post

Year 2010

Sample size justification

As I mentioned in an earlier webpage, I am talking to some publishers about writing a second book. The working title is "Jumpstart Statistics: How to Restart Your Stalled…

Tentative table of contents for my second book

*Blog post

Year 2010

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Jumpstart Statistics, a proposal for my second book

*Blog post

Year 2010

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Salary survey for Biostatisticians

*Blog post

Year 2010

Being updated

Human side of statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Another counter-intuitive probability problem

*Blog post

Year 2010

Being updated

Probability

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Can political questions be resolved by science

*Blog post

Year 2010

Being updated

Human side of statistics

Earlier versions are here and here.

Resources using Stack Overflow

*Blog post

Year 2010

Being updated

Teaching resources

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Classic references in Statistics

*Blog post

Year 2010

Being updated

Teaching resources

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

The SPSS t-test is confusing

*Blog post

Year 2010

Being updated

SPSS software

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What I use for talks instead of Powerpoint

*Blog post

Year 2010

Being updated

Presenting research

Someone on LinkedIn asked a question about what technologies people use for their presentations (laptop, flipchart, or whiteboard). For most of my presentations, I use none…

Fitting a new class of nonlinear regression models

*Blog post

Year 2010

Being updated

Nonlinear regression

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What I use for talks instead of Powerpoint

*Blog post

Year 2010

Being updated

Presenting research

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

The futility of small sample sizes for evaluating a binary outcome

*Blog post

Year 2010

Being updated

Small sample size issues

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

An example of a bad survey

*Blog post

Year 2010

Being updated

Survey design

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

An interesting alternative to power calculattions

*Blog post

Year 2010

Being updated

Sample size justification

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Minimum sample size needed for a time series prediction

*Blog post

Year 2010

Being updated

Time series

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Computing power for an interaction in linear regression

*Blog post

Year 2010

Being updated

Linear regression

Sample size justification

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What is the premier conference for statistical consulting

*Blog post

Year 2010

Being updated

Teaching resources

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Lessons learned the hard way. Don’t presume to know how your software handles missing value codes

*Blog post

Year 2010

Being updated

Missing data

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Making simple modifications to a graph in SPSS

*Blog post

Year 2010

Being updated

Graphical display

SPSS software

Earlier versions are here and here.

How I got started in my career as an independent statistical consultant

*Blog post

Year 2010

Being updated

Human side of statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

How do I handle criticism

*Blog post

Year 2010

Being updated

Human side of statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

How to avoid charges of plagiarism

*Blog post

Year 2010

Being updated

Writing research papers

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Withdrawing from a study and taking your data with you

*Blog post

Year 2010

Being updated

Ethics in research

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Lessons learned the hard way: don’t throw good money after bad

*Blog post

Year 2010

Being updated

Data management

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

More discussion on instrumental variables

*Blog post

Year 2010

Being updated

Instrumental variables

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What is a good surrogate measure for socioeconomic status

*Blog post

Year 2010

Being updated

Evidence Based Medicine

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Interpreting p-values in a published abstract, part 1

*Blog post

Year 2010

Being updated

Hypothesis testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Quiz about p-values

*Blog post

Year 2010

Being updated

Hypothesis testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Using entropy and the surprisal value to measure the degree of agreement with the consensus finding

*Blog post

Year 2010

Information theory

One of the research problems that I am working on involves evaluation of a subjective rating system. I have been using information theory to try to identify objects where…

What makes a good website?

*Blog post

Year 2010

Being updated

Website details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Should I learn R instead of SAS

*Blog post

Year 2010

Being updated

R software

SAS software

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Dealing with a large text file that crashes your computer

*Blog post

Year 2010

Data science

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What to say when any data analysis is pointless

*Blog post

Year 2010

Being updated

Human side of statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Calculating weights to correct for over and under sampling

*Blog post

Year 2010

Sampling

Someone asked how to use weights to adjust for the fact that certain strata in a study were recruited more vigorously than other strata. For example, suppose you sampled at…

Ordinal surprisals

*Blog post

Year 2010

Being updated

Information theory

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Can sex be an outcome variable?

*Blog post

Year 2010

Being updated

Modeling issues

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Ordinal entropy

*Blog post

Year 2010

Being updated

Information theory

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Finding duplicate records in a 19 million record database

*Blog post

Year 2010

Being updated

Data science

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Is intuition real?

*Blog post

Year 2010

Critical appraisal

Someone asked if intuition is real.

Abstract submitted to Missouri Regional Life Sciences Summit

*Blog post

Year 2010

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Exponential interpolation

*Blog post

Year 2010

Being updated

Modeling issues

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Fan page for The Monthly Mean

*Blog post

Year 2010

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Meta-analysis for a single mean estimate

*Blog post

Year 2010

Systematic overviews

Someone noted that the usual meta analysis is carried out for the study on two treatment groups, usually for a difference in means. What if you had several studies…

Statistical Literacy for Medical Librarians

*Blog post

Year 2010

Being updated

Professional details

Earlier versions are here and here.

Survey of librarians in the Midcontinental Chapter of the Medical Library Association

*Blog post

Year 2010

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Consulting remotely versus consulting in person

*Blog post

Year 2010

Being updated

Human side of statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Humility is a good thing for researchers to have

*Blog post

Year 2010

Being updated

Human side of statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What are the characteristics of a good consultant

*Blog post

Year 2010

Being updated

Human side of statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Proposed poster for the Missouri Regional Life Sciences Summit

*Blog post

Year 2010

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Finding the standard deviation for a power calculation

*Blog post

Year 2009

Being updated

Sample size justification

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Facebook account

*Blog post

Year 2010

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Abstracts for a possible upcoming talk

*Blog post

Year 2010

Professional details

I might be asked to give a talk in February and I wanted to offer two possible choices. Here are the titles and abstracts of those talks.

Masters or Phd in Statistics?

*Blog post

Year 2010

Human side of statistics

Someone asked me about careers in Statistics and if you get the best career with a Masters degree or a PhD. That’s a very subjective choice and individual preferences should…

SPSS or Stata?

*Blog post

Year 2010

Being updated

SPSS software

Stata software

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Where can I find free online textbooks

*Blog post

Year 2010

Being updated

Teaching resources

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

The first three steps in selecting an appropriate sample size

*Blog post

Year 2009

Being updated

Sample size justification

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Lost page

*Blog post

Year 2010

Being updated

Website details

Here is a series of recommended books, journal articles, and websites that I had collected during 2010. There is no particular topic and no special order.

Power calculations for comparison of Poisson counts across two groups

*Blog post

Year 2010

Being updated

Poisson regression

Sample size justification

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What is residual confounding?

*Blog post

Year 2010

Being updated

Linear regression

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

My life so far, fails to meet expectations

*Blog post

Year 2010

Being updated

Human side of statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Entering and analyzing data from a two by two table

*Blog post

Year 2009

Being updated

SPSS software

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Randomly generating simple math problems using R

*Blog post

Year 2009

Being updated

R software

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Generating multinomial random variables in Excel

*Blog post

Year 2009

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Jump start statistics for beginning researchers

*Blog post

Year 2009

Being updated

Teaching resources

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Rotating locations

*Blog post

Year 2009

Being updated

Research design

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Sneaking ineligible patients into a clinical trial

*Blog post

Year 2009

Being updated

Fraud in research

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What is a normal probability plot?

*Blog post

Year 2009

Being updated

Probability distributions

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Data layout for an ROC curve

*Blog post

Year 2009

Being updated

Diagnostic testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Accounting for clusters in an individually randomized clinical trial

*Blog post

Year 2009

Randomization in research

I have a clinical trial with clusters (the clusters are medical practice), but unlike a cluster randomized trial, I am able to randomize within each cluster. From what I’ve…

Use of Likert data with ANOVA

*Blog post

Year 2009

Being updated

Analysis of variance

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Are we statisticians gods?

*Blog post

Year 2009

Being updated

Human side of statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Can I stop this study?

*Blog post

Year 2009

Being updated

Early stopping

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

The problem with being too sensitive

*Blog post

Year 2009

Being updated

Diagnostic testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Simple longitudinal data analyses, part 1

*Blog post

Year 2009

Being updated

Longitudinal data

Earlier versions are here and here.

Getting a good cut-off

*Blog post

Year 2009

Being updated

Diagnostic testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Power for a three arm experiment

*Blog post

Year 2009

Being updated

Sample size justification

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

The controversy over standardized beta coefficients

*Blog post

Year 2009

Being updated

Linear regression

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Tentative training schedule

*Blog post

Year 2009

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Standard error for an odds ratio

*Blog post

Year 2009

Being updated

Measuring benefit and risk

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Formula for multiple imputation

*Blog post

Year 2009

Being updated

Missing data

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Do multiple time points require a Bonferroni adjustment

*Blog post

Year 2009

Being updated

Multiple comparisons

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

The perils of self-evaluation

*Blog post

Year 2009

Being updated

Critical appraisal

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Institute of Medicine report on conflict of interest

*Blog post

Year 2009

Being updated

Conflict of interest

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Data that IRBs should collect about themselves

*Blog post

Year 2009

Being updated

Ethics in research

Earlier versions are here and here.

The surprisal matrix and applications to exploration of very large discrete data sets

*Blog post

Year 2009

Being updated

Information theory

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

NYTimes advice on increasing website traffic

*Blog post

Year 2009

Being updated

Website details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Is this a case-control design?

*Blog post

Year 2009

Being updated

Epidemiology

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Can I use you as a teaching example?

*Blog post

Year 2009

Being updated

Teaching resources

Website details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Calculating NNT for

*Blog post

Year 2009

Being updated

Measuring benefit and risk

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Calculating NNT for infection rates

*Blog post

Year 2009

Being updated

Measuring benefit and risk

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Two business contacts

*Blog post

Year 2009

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Short biography

*Blog post

Year 2009

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

I love to write

*Blog post

Year 2009

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Five points or seven points on a survey scale

*Blog post

Year 2009

Being updated

Survey design

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Good papers for a journal club

*Blog post

Year 2009

Being updated

Teaching resources

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Locating individual points on an ROC curve

*Blog post

Year 2009

Being updated

Diagnostic testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Sample size calculation for a logistic regression model

*Blog post

Year 2009

Being updated

I might need to do a sample size justification for a logistic regression model. How would this be done? Let me outline some simple cases.

Fewer than 10 events per variable

*Blog post

Year 2009

Being updated

Small sample size issues

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Acknowledging the

*Blog post

Year 2009

Writing research papers

A while back you assisted me with stats on my paper. I am finally ready to submit and wanted to know how I should appropriately acknowledge you for your participation since…

Interpreting a negative autocorrelation

*Blog post

Year 2009

Being updated

Time series

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Calibrating information

*Blog post

Year 2009

Being updated

Information theory

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Updates for 2009

*Blog post

Year 2009

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Changes in the adjusted hazard

*Blog post

Year 2009

Being updated

Survival analysis

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Drawing simple mathematical graphs

*Blog post

Year 2009

Being updated

Graphical display

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A simple example of joint and conditional entropy

*Blog post

Year 2009

Being updated

Information theory

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Maybe Powerpoint isn’t so bad

*Blog post

Year 2009

Being updated

Presenting research

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Analyzing bad data

*Blog post

Year 2009

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

DNA binding image

*Blog post

Year 2009

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

New Bioinformatics degree

*Blog post

Year 2009

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A sportswriter tackles the Monty Hall problem

*Blog post

Year 2009

Being updated

Probability

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What is the effect of an unmeasured covariate?

*Blog post

Year 2009

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Developing a website logo

*Blog post

Year 2009

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A false sense of frugality

*Blog post

Year 2008

Being updated

Data management

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Viewing SPSS and SAS output without buying SPSS and SAS

*Blog post

Year 2008

Being updated

SAS software

SPSS software

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Using a sub-optimal approach in meta-analysis

*Blog post

Year 2008

Being updated

Systematic overviews

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Zotero, The Next Generation Research Tool

*Recommendation

Year 2008

Being updated

Writing research papers

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What is the Lan-DeMets approach to interim analysis

*Blog post

Year 2008

Being updated

Early stopping

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Updates for 2008

*Blog post

Year 2008

Being updated

Obsolete page

Professional details

This page is osolete. I am keeping it around for mostly nostalgic reasons.

The Myth of Equipoise in Phase 1 Clinical Trials

*Recommendation

Year 2008

Being updated

Systematic overviews

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

The statistician who supposes that…

*Quotation

Year 2008

Being updated

Ethics in research

Interesting quote: The statistician who supposes that his main contribution to the planning of an experiment will involve statistical theory, finds repeatedly that he makes…

Explaining CART models in simple terms

*Blog post

Year 2008

Being updated

Data mining

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Four assumptions of multiple regression that researchers should always test

*Recommendation

Year 2008

Being updated

Linear regression

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

The Myth of Equipoise in Phase 1 Clinical Trials

*Recommendation

Year 2008

Being updated

Ethics in research

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Reading abstracts instead of the full paper

*Blog post

Year 2008

Being updated

Critical appraisal

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Statisticians are not gatekeepers

*Blog post

Year 2008

Being updated

Human side of statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Helping Doctors and Patients Make Sense of Health Statistics

*Recommendation

Year 2008

Being updated

Teaching resources

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Comparing a set of microarray experiments to a model experiment

*Blog post

Year 2008

Being updated

Data science

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Components of placebo effect, Randomised controlled trial in patients with irritable bowel syndrome

*Recommendation

Year 2008

Being updated

Placebos in research

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Regression with SAS. Additional coding systems for categorical variables

*Recommendation

Year 2008

Being updated

Analysis of variance

SAS software

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

To be updated

*Blog post

Year 2008

Being updated

Survey design

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Refusing to analyze a data set

*Blog post

Year 2008

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A standard deviation that is too big for its own britches

*Blog post

Year 2008

Being updated

Descriptive statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Computing a difference between first and last variables

*Blog post

Year 2008

Data management

SPSS software

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Intervening variable

*Recommendation

Year 2008

Being updated

Hypothesis testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Variables and hypotheses

*Recommendation

Year 2008

Being updated

Hypothesis testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Example of power calculation for a repeated measures design

*Blog post

Year 2008

Being updated

Sample size justification

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Errors in statistical methodology

*Blog post

Year 2008

Being updated

Critical appraisal

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Biostatistics or Health Informatics programs in or near Kansas City

*Blog post

Year 2008

Being updated

Teaching resources

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Defending Bonferroni

*Blog post

Year 2008

Being updated

Multiple comparisons

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Interpretations for a two by two table

*Blog post

Year 2008

Being updated

Probability concepts

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Normality assumptions for the paired t-test

*Blog post

Year 2008

Being updated

Hypothesis testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

T-test with 3 treatment values and 2 controls

*Blog post

Year 2008

Being updated

Small sample size issues

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Example of power calculation for a repeated measures design

*Blog post

Year 2008

Being updated

Sample size justification

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A simple example of overfitting

*Blog post

Year 2008

Being updated

Modeling issues

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

How do I fit a piecewise linear regression

*Blog post

Year 2008

Being updated

Linear regression

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What’s new in SPSS 17

*Blog post

Year 2008

Being updated

SPSS software

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Evaluating private conflicts of interest

*Blog post

Year 2008

Being updated

Conflict of interest

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Can I ask you a question

*Blog post

Year 2008

Being updated

Website details

Dear Professor Mean,

Comparing pre and post data with a parallel control group

*Blog post

Year 2008

Being updated

Multilevel models

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Processing skip fields in SPSS

*Blog post

Year 2008

Being updated

SPSS software

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Venn diagrams with proportional areas

*Blog post

Year 2008

Being updated

Graphical display

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Links and references that I need to add

*Blog post

Year 2008

Being updated

Website details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Can an outcome with three levels be used in logistic regression

*Blog post

Year 2008

Being updated

Logistic regression

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Categorizing entropy values

*Blog post

Year 2008

Being updated

Information theory

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Jackknife applied to entropy calculations

*Blog post

Year 2008

Being updated

Information theory

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Use of entropy measures for sperm morphology classification

*Blog post

Year 2008

Being updated

Information theory

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

How do you compute a continuity correction for a confidence interval

*Blog post

Year 2008

Confidence intervals

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Comparisons involving distinct groups collected at different times and with different methods

*Blog post

Year 2008

Being updated

Observational studies

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What does “population-based” mean?

*Blog post

Year 2008

Being updated

Writing research papers

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Where did you get that formula for the confidence interval

*Blog post

Year 2008

Confidence intervals

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Multiple email accounts

*Blog post

Year 2008

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

The case of Ranjit Kumar Chandra

*Blog post

Year 2008

Ethics in research

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Applying the sequence logo concept to data quality

*Blog post

Year 2008

Being updated

Data quality

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Checks for data quality using metadata

*Blog post

Year 2008

Data management

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Controversies with a test for ovarian cancer

*Blog post

Year 2008

Being updated

Ethics in research

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Entropy as a measure of data quality across multiple variables

*Blog post

Year 2008

Being updated

Information theory

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Where to look for information in a controversial area

*Blog post

Year 2008

Critical appraisal

Being updated

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What resources are available for fellows

*Blog post

Year 2008

Being updated

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Source for sample size formula

*Blog post

Year 2008

Being updated

Sample size justification

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Is there a scientific basis for EBM?

*Blog post

Year 2008

Being updated

Evidence-based medicine

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Another inquiry about slash and burn models

*Blog post

Year 2008

Being updated

Logistic regression

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Social networking as a business tool

*Blog post

Year 2008

Being updated

Human side of statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Cumulative entropy as a measure of data quality

*Blog post

Year 2008

Being updated

Information theory

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

To be updated

*Blog post

Year 2008

Being updated

Multiple comparisons

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Anti-intellectualism

*Quotation

Year 2008

Being updated

Critical appraisal

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Interval scale for count data

*Blog post

Year 2008

Being updated

Descriptive statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Harsh sanctions are only part of the solution

*Blog post

Year 2008

Being updated

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Reporting of adverse events

*Blog post

Year 2008

Adverse events

Being updated

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Comparing two proportions out of the same multinomial population

*Blog post

Year 2008

Being updated

Multinomial probabilities

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Resources from the Statistical Consulting Section of the American Statistical Association

*Blog post

Year 2008

Human side of statistics

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Naming conventions for variables

*Blog post

Year 2008

Being updated

Data management

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Business aspects of an independent statistical consultant

*Blog post

Year 2008

Being updated

Human side of statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What does the FDA think about Bayesian statistics

*Blog post

Year 2008

Being updated

Bayesian statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Should I abandon FrontPage?

*Blog post

Year 2008

Obsolete page

Website details

This page is obsolete, but I am keeping it around for sentimental reasons. Note: 2025-07-19. I did try KompoZer and it was okay, but ended up using other software. I am not…

Plug for accrual research

*Blog post

Year 2008

Accrual problems

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

My very first meta-analysis

*Blog post

Year 2008

Being updated

Systematic overviews

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Godwin’s Law

*Blog post

Year 2008

Accrual problems

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Mail and calendar software I use in my new job

*Blog post

Year 2008

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What distribution does this data come from

*Blog post

Year 2008

Being updated

Modeling issues

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Survey results from nine out of thirty six

*Blog post

Year 2008

Being updated

Small sample size issues

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Where can I learn more about Statistics?

*Blog post

Year 2008

Being updated

Teaching resources

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Software for bootstrap and resampling

*Blog post

Year 2008

Being updated

Resampling methods

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Can I use some material from your website

*Blog post

Year 2008

Being updated

Website details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Getting on and off various email lists

*Blog post

Year 2008

Being updated

Teaching resources

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Hire me as a consultant

*Blog post

Year 2008

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A misleading bar graph

*Blog post

Year 2008

Being updated

Graphical display

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Undeclared missing code leads

*Blog post

Year 2008

Being updated

Missing data

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Using Google to search through my website

*Blog post

Year 2008

Being updated

Website details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

How to report a one-tailed Fisher’s Exact Test

*Blog post

Year 2008

Being updated

Hypothesis testing

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Pearson correlation and ordinal data

*Blog post

Year 2008

Being updated

Linear regression

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Pearson correlation and ordinal data don’t mix

*Blog post

Year 2008

Being updated

Linear regression

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Where did that standard deviation come from

*Blog post

Year 2008

Being updated

Sample size justification

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Distrust of a Bayesian

*Blog post

Year 2008

Bayesian statistics

Being updated

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How many files

*Blog post

Year 2008

Being updated

Website details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Bootstrap estimates of the standard error

*Blog post

Year 2008

Unusual data

A regular correspondent (JU) on the MEDSTATS email discussion group asked about using the bootstrap to estimate the standard error of the mean in a simple case with 9 data…

Can I run a quantitative analysis on this data?

*Blog post

Year 2008

Being updated

Small sample size issues

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Running R on a web server

*Blog post

Year 2008

Being updated

R software

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Modeling a declining count variable

*Blog post

Year 2008

Poisson regression

Rmarkdown code

I’ve been working on an interesting project that requires Poisson regression. A company sends out a mailing and gets a certain number of telephone calls back on each of the…

Criticism of random effects in a meta-analysis

*Blog post

Year 2008

Being updated

Systematic overviews

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Eliciting a prior distribution for rejection/refusal rates

*Blog post

Year 2008

Accrual problems

Being updated

I got a question about the Bayesian model for rejection/refusal rates. I had used three prior distributions in my calculations, a Beta(10,40), a Beta(45,5), and a…

When does heterogeneity become a concern?

*Blog post

Year 2008

Being updated

Analysis of variance

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Why it’s impossible to keep a resume current

*Blog post

Year 2008

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

How wide can you make a line of your web page?

*Blog post

Year 2008

Being updated

Website details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A simple Bayesian model for

*Blog post

Year 2008

Accrual problems

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A short biography that can be used as an introduction

*Blog post

Year 2008

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Why does a Bayesian approach make sense for monitoring accrual?

*Blog post

Year 2008

Being updated

Bayesian statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Slipped deadlines and sample size shortfalls in a random sample of research studies

*Blog post

Year 2008

Accrual problems

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Monitoring refusals and exclusions in a clinical trial

*Blog post

Year 2008

Being updated

Accrual problems

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Directions to my new office

*Blog post

Year 2008

Obsolete page

This page is obsolete. I am keeping it around mostly for nostalgic reasons.

Nomination for the Kreamer Award for Research Excellence

*Blog post

Year 2008

Being updated

Professional details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Upcoming topics in Poisson regression

*Blog post

Year 2008

Obsolete page

This page is obsolete. I am keeping it around mostly for nostalgic reasons.

Evidence Based Medicine for patients

*Blog post

Year 2008

Being updated

Information searching

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A brief overview of instrumental variables

*Blog post

Year 2008

Being updated

Unusual data

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A simple math error

*Blog post

Year 2008

Being updated

Website details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What does one-third of the way through a study mean?

*Blog post

Year 2008

Being updated

Early stopping

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Calculating statistics on whole numbers

*Blog post

Year 2008

Being updated

Descriptive statistics

Writing research papers

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

An alternative to the p-value

*Blog post

Year 2008

Being updated

Hypothesis testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Why we need case studies of research ethics in graphic novel format

*Blog post

Year 2008

Ethics in research

I was asked to provide some justification for a project I am working on, case studies in research ethics using a graphic novel format. Here is what I wrote.

What sort of statistical training is needed for basic scientists?

*Blog post

Year 2008

Being updated

Teaching resources

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Statistics for Boards

*Blog post

Year 2008

Being updated

Teaching resources

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

When a client asks for a bad analysis

*Blog post

Year 2008

Being updated

Human side of statistics

Multiple comparisons

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Presenting unadjusted and adjusted estimates side by side

*Blog post

Year 2008

Being updated

Modeling issues

Writing research papers

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

ROC curve for an imperfect gold standard

*Blog post

Year 2008

Being updated

Diagnostic testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Moving content to a private site

*Blog post

Year 2008

Being updated

Website details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

ROC curve for an imperfect gold standard

*Blog post

Year 2008

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Simplifying repeated measurements

*Blog post

Year 2008

Being updated

Multilevel models

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Losing web pages in the mass of information

*Blog post

Year 2008

Being updated

Website details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Calculating NNT for observational studies

*Blog post

Year 2008

Being updated

Measuring benefit and risk

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Assessing the assumption of an exponential distribution

*Blog post

Year 2008

Being updated

Modeling issues

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What is a critical value?

*Blog post

Year 2008

Being updated

Hypothesis testing

Someone wrote in asking about the difference between a p-value and a critical value. I define a p-value on my web pages already. The critical value is typically a percentile…

Multiple methods for computing percentiles

*Blog post

Year 2008

Descriptive statistics

A recent discussion on the Medstats group highlighted some of the confusion about computing percentiles. I use a simple formula. If you want the pth percentile of a set of n…

Does prevalence affect sensitivity

*Blog post

Year 2008

Being updated

Diagnostic testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A simple example of a Kaplan-Meier curve

*Blog post

Year 2008

Being updated

Survival analysis

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

How do you analyze safety data

*Blog post

Year 2008

Adverse events

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Finding only the important studies

*Blog post

Year 2008

Being updated

Systematic overviews

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What have you changed your mind about

*Blog post

Year 2008

Being updated

Teaching resources

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Too much power and precision?

*Blog post

Year 2008

Sample size justification

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

The post-modern assault on evidence-based medicine, part 3

*Blog post

Year 2008

Being updated

Critical appraisal

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

High altitude effects on athletic performance

*Blog post

Year 2008

Being updated

Poisson regression

Teaching resources

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What statistic should I use when?

*Blog post

Year 2008

Being updated

Analysis of variance

Linear regression

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Type III error

*Blog post

Year 2008

Being updated

Hypothesis testing

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

I hate bad research examples

*Blog post

Year 2008

Being updated

Teaching resources

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Cytel software has developed a Poisson

*Blog post

Year 2008

Being updated

Accrual problems

This page is missing, both in the current version in my blog and in earlier versions. I should delete these pages totally and pretend that they never existed.

New format for articles, books, and websites

*Blog post

Year 2008

Being updated

Website details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

New personal pages

*Blog post

Year 2008

Being updated

Personal details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

To be updated

*Blog post

Year 2008

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Reliable diagnosis of cataracts

*Blog post

Year 2008

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

To be updated

*Blog post

Year 2008

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Resources for Statistical Evidence in Medical Trials

*Blog post

Year 2008

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Reviews of “Statistical Evidence.”

*Blog post

Year 2008

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

The glitter of…

*Quotation

Year 2008

Critical appraisal

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

When should you use a log transformation?

*Blog post

Year 2007

Linear regression

How do I know whether it is appropriate to use a log transformation for my data?

Who wrote the law that mandates PowerPoint?

*Blog post

Year 2007

Presenting research

A recent filler item in BMJ, The PowerPoint presentation, written by David Isaacs, Stephen Isaacs, and Dominic Fitzgerald, provided a light hearted view of the bad habits…

Analyzing data under an Intention to Treat model

*Blog post

Year 2007

Randomization in research

I need to know how to analyze a data set using the intention to treat principle.

The post-modern assault on evidence-based medicine

*Blog post

Year 2007

Critical appraisal

I never got around to submitting an article to Skeptic Magazine, but here is an update of something I wrote back in 2007 about post-modern philosophy and evidence based…

A Poisson regression model with interactions

*Blog post

Year 2007

Poisson regression

I got a question about how to interpret an interaction term in a Poisson regression model. The first thing to remember is that the estimates in a Poisson regression model…

No longer the sole statistician?

*Blog post

Year 2007

Professional details

Children’s Mercy Hospital is hiring a second statistician. Hooray! It’s a great place to work and I’m hoping we can hire someone quickly. The links to describe the position…

Testing for an increasing trend in a proportion

*Blog post

Year 2007

Logistic regression

Someone asked me how to see if a sequence of four proportions is showing a significant increase over time. The data represents the proportion of imaging studies that are…

Tracking adverse events during kidney biopsy

*Blog post

Year 2007

Adverse events

This is a major revision of the March 14, 2007 and April 5, 2007 weblog entries. I have been helping a colleague who is interested in monitoring the safety of kidney biopsy…

What, exactly, is a child?

*Blog post

Year 2007

Children in research

I’m updating a talk on research issues associated with pediatric treatments. Before I start throwing around terms like “paediatric” and “child,” I should take some time to…

Tracking central line infections over time

*Blog post

Year 2007

Adverse events

I’m working with a group that is tracking central line infections over time. There were 22 infections over the previous year, and the infants were divided into five risk…

My page names are too long

*Blog post

Year 2007

Website details

About three years ago, I started using longer names for my webpages. It makes it easier for me to maintain and upgrade these pages. So instead of a short name like…

Monitoring adverse events during peritoneal dialysis

*Blog post

Year 2007

Adverse events

One of the doctors I was working with had an interesting data set examining adverse events in patients with peritoneal dialysis. These patients start treatment with…

Stair step interpolation in R

*Blog post

Year 2007

Graphical display

R software

I am working on some charts that show discrete (sudden) jumps at specific time points. This requires the use of stair step interpolation, because if you just connected the…

NNH talk update

*Blog post

Year 2007

Adverse events

Last year, I gave a talk for PharmaIQ about continuous monitoring of the number needed to harm. I want to update this talk for a second audience in December. Here’s the…

Reforming conflict of interest statements

*Blog post

Year 2007

Conflict of interest

In a recent talk, I was asked to disclose any conflicts of interest. I did so, but I also commented that the organization I was speaking to, as well as most other…

Postlude to my Dallas talk

*Blog post

Year 2007

Diagnostic testing

I gave a talk this morning to the American College of Allergy, Asthma & Immunology (ACAAI). I documented my preparations for this talk on my webpages and wanted to share…

Grow up and learn how to do Statistics

*Blog post

Year 2007

Human side of statistics

I attended a talk by Dr. Martha Curley about parental presence during invasive procedures and resuscitation. Early in the talk, Dr. Curley mentioned a bell shaped curve and…

Handout for diagnostic testing

*Blog post

Year 2007

Diagnostic testing

I have been busy preparing a handout describing the basics of diagnostic testing (e.g., sensitivity and specificity), the medical issues associated with these tests (e.g.…

New categories needed

*Blog post

Year 2007

Broken link

Website details

I need to develop some new categories. The first will discuss report cards, league tables, and other measures of hospital and individual performance. The pages I have on…

Open-access (OA) journals and their impact on research and the practice of medicine (created October 18, 2007

*Blog post

Year 2007

Broken link

Writing research papers

This talk will cover the following topics:

Revising my definition section

*Blog post

Year 2007

Website details

I have a section on definitions and it is an odd mix of things. I want to simplify these pages by separating examples of how to calculate a particular statistic from the…

Unused resources for my open access talk

*Blog post

Year 2007

Broken link

Writing research papers

I am giving a talk on Open Access journals at the Grand Rounds for CMH on Thursday, October 17. See my web summary and my pdf slides. Here are some resources which (in the…

Illustrations for a case study of the TGN 1412 trial (created 2007-10-12).

*Blog post

Year 2007

Ethics in research

I am working with a graphic artist to produce some illustrations to help explain what happened during the disastrous TGN1412 trial. The general structure of these…

Confidence interval for a rate

*Blog post

Year 2007

Confidence intervals

Poisson regression

How do you calculate a confidence interval for a rate?

Case study of accrual in a clinical trial, part 2

*Blog post

Year 2007

Accrual problems

I received additional accrual data on a clinical trial I am monitoring. To review, the trial started on August 28, 2007 and will continue until January 31, 2008, for a total…

Seminar on Open Access Journals

*Blog post

Year 2007

Writing research papers

I was inspired by a talk by Jim Pitman, President of the IMS, at the Joint Statistical Meetings in August, “Open Access to Professional Information” so when an opportunity…

Educational and networking opportunities for statisticians in the Kansas City area

*Blog post

Year 2007

Teaching resources

There are three groups that offer seminars, training classes and informal networking opportunities for statisticians in the Kansas City area.

An alternate way of viewing accrual

*Blog post

Year 2007

Accrual problems

I was talking about a project with a fellow in Emergency Medicine and during the discussion realized a different way of looking at accrual in a clinical trial. She plans to…

Help for Statistics at UMKC and KUMC

*Blog post

Year 2007

Obsolete page

Professional details

Note: a large number of people listed here have moved on.

Alphabetical bookmark list

*Blog post

Year 2007

Obsolete page

Website details

This page is obsolete. I am keeping it around for nostalgic reasons.

Html debris copied from other websites

*Blog post

Year 2007

Obsolete page

Website details

[Note: These stray tags are no longer an issue since I converted to using blogdown to create webpages.]

The latest word on my promotion

*Blog post

Year 2007

Professional details

In previous weblog entries,

Patterns to look for in a histogram

*Blog post

Year 2007

Graphical display

When you plot your data in a histogram (or a stem and leaf diagram), you should look for patterns. Here are examples of three of the most important ones.

The order of entering interactions into a model

*Blog post

Year 2007

Logistic regression

I like your titanic example! But shouldn’t you enter the interaction term on a second step following entry of the main effects on the first step? If you enter the terms all…

What does a statistician do all day?

*Blog post

Year 2007

Human side of statistics

I have to write up a job description for a statistician. This includes essential functions and important functions. Here are two examples. The first is how my own job was…

How many webpages have I written?

*Blog post

Year 2007

Administrative details

Obsolete page

[Note: this page shows counts from the year 2007. The website has grown substantially since then.]

Case study of accrual in a clinical trial

*Blog post

Year 2007

Accrual problems

Someone came by today with a project where he wants to monitor the accrual in a clinical trial. The trial started on August 28, 2007 and will continue until January 31…

Is my confidence interval wide?

*Blog post

Year 2007

Confidence intervals

Dear Professor Mean, I have a case-control design. Among the cases, 271 were exposed and 317 were unexposed. Among the controls, 125 were exposed and 976 were unexposed.…

My promotion application

*Blog post

Year 2007

Professional details

In previous weblog entries (see below), I discussed the process for applying for a promotion to Full Professor. Yesterday, I turned in a completed a promotion application. I…

Resources for grant writers

*Blog post

Year 2007

Broken link

Grant writing

If you are interested in writing a grant, there are a lot of free resources that you can consult. Many of these are written by the same people who hand out the grant money…

Extra information for the resume of Stephen D. Simon

*Blog post

Year 2007

Obsolete page

Professional details

Notice to headhunters: I am not looking for a job. I am posting this resume to help with my collaborative efforts with others outside Children’s Mercy Hospital.

External scholars needed to review my promotion materials

*Blog post

Year 2007

Professional details

Although I do all my work at Children’s mercy Hospital, I have a joint appointment as Associate Professor in the School of Medicine at the University of Missouri-Kansas…

Are we assuming a normal sample or a normal population?

*Blog post

Year 2007

Modeling issues

I’m fitting an ANOVA model to a sample of 25 observations, and the data is quite skewed. I’m quite worried about this, but my husband reassures me that this is not a…

What makes pediatric research different?

*Blog post

Year 2007

Children in research

I may be asked to give a repeat performance of Stats #53: Signal Detection Strategies for Paediatric Treatments. This is a three hour class that I gave last year in London.…

Analyzing data from a simple crossover design

*Blog post

Year 2007

Analysis of variance

A doctor brought me some data from a crossover design and asked me to help analyze it. The analysis was a bit trickier than I had expected, so I reviewed some of the…

Common sources of confusion in a class on quality control

*Blog post

Year 2007

Control charts

I presented a training class, Stats #18: Quality Control: A Hands-On Workshop, for the American Society for Andrology. The major emphasis was on the computation of control…

Accrual grant, Round 3

*Blog post

Year 2007

Accrual problems

Last year, I applied for a Kansas City Area Life Sciences Institute (KCALSI) Research Development grant. It was not funded, but a subsequent grant that I submitted to the…

How good is my prediction?

*Blog post

Year 2007

Modeling issues

I have two time series of data, one actual and one predicted. Since I’m quite new to statistical methods, I would like to know what methods are used to evaluate the…

Does promoting your book constitute a conflict of interest?

*Blog post

Year 2007

Conflict of interest

I give lots of talks and I usually put in a plug for my book, Statistical Evidence in Medical Trials. I even promote my book in the signature file that I put at the bottom…

Need for a conflict of interest policy

*Blog post

Year 2007

Conflict of interest

I attended a very interesting session at the Joint Statistical Meetings last week on conflict of interest. I asked a question during the session that seemed quite obvious to…

Justifying the sample size for a microarray study

*Blog post

Year 2007

Data mining

Sample size justification

I’m helping out with a grant proposal that is using microarrays for part of the analysis. A microarray is system for quantitative measurement of circulating mRNA in human…

Which expert should you believe?

*Blog post

Year 2007

Critical appraisal

There’s a common saying in research circles that goes something like this: “For every PhD, there is an equal and opposite PhD.” That saying is certainly true in my…

Bibliography of papers relating to predicting accrual in clinical trials

*Blog post

Year 2007

Accrual problems

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Should I use the heteroscedastic t-test?

*Blog post

Year 2007

Hypothesis testing

I am using Excel to do a t-test to see if there is a difference between blood glucose levels in babies who received 2 different treatments. I want to know if the new…

Conflict of interest in the Wakefield MMR study

*Blog post

Year 2007

Children in research

Conflict of interest

Ethics in research

An interesting case study in conflict of interest (perhaps a bit too complex to be described fairly in this brief weblog entry) involves a controversial paper. The lead…

Continuing education questions for a talk on diagnostic tests

*Blog post

Year 2007

Diagnostic testing

As part of my talk to the American College of Allergy, Asthma & Immunology, I have been asked to present two questions related to my topic (Use of Diagnostic Tests for…

Classic calculations for a diagnostic test

*Blog post

Year 2007

Diagnostic testing

I created a table that illustrates many of the classic calculations for a diagnostic test.

Conflict of interest list

*Blog post

Year 2007

Conflict of interest

Professional details

I was asked to fill out a conflict of interest form for a talk I will be giving in December. While I have not gotten any money directly from drug companies recently, I do…

I don’t want to use a randomized trial

*Blog post

Year 2007

Observational studies

Randomization

An email on the MedStats group outlines a new treatment that is:

Code for drawing new likelihood ratio slide rule

*Blog post

Year 2007

Diagnostic testing

I have made some minor changes to my likelihood ratio slide. The original code was lost somewhere, so I wrote some new code and added documentation. I also changed the…

Code for drawing new likelihood ratio slide rule

*Blog post

Year 2007

Diagnostic testing

Rmarkdown code

I have made some minor changes to my likelihood ratio slide. The original code was lost somewhere, so I wrote some new code and added documentation. I also changed the…

The research world is not black and white

*Blog post

Year 2007

Critical appraisal

I was asked to review a commentary about studies involving remote healing (which includes prayer studies as a subgroup). It is not available yet on the web, but I’ll try to…

Recommendations from Sackett et al for evaluating a diagnostic test

*Blog post

Year 2007

Diagnostic testing

There is a lot of controversy about diagnostic testing, and I have mentioned some of these controversies in other weblog entries. I wanted to review what the experts say…

The stubborn insistence on placebos

*Blog post

Year 2007

Placebos in research

The patients who volunteer for a randomized trial are sacrificing a great deal of autonomy. They giving up the right to determine which drug they get and they are ceding…

How two bad control groups can add up to one good comparison

*Blog post

Year 2007

Observational studies

Many observational studies are criticized (often deservedly) for having a bad control group. If you choose a bad control group, you create an unfair (apples to oranges)…

The debate about historical control groups

*Blog post

Year 2007

Broken link

Observational studies

Someone on the Evidence Based Medicine email discussion group asked about how to appraise a “before and after” design. This is effectively the same as using a historical…

The trouble with apples and oranges

*Blog post

Year 2007

Observational studies

Placebos in research

I am still working on the details of a presentation for the Kansas City University of Medicine and Biosciences. They want me to talk at lunch during the 2007 Homecoming CME…

I deserve a promotion

*Blog post

Year 2007

Professional details

Please note a related weblog entry: External scholars needed to review my promotion materials.

Why the plus one in the percentile formula?

*Blog post

Year 2007

Descriptive statistics

I was reviewing your page on the interquartile range and was wondering why the formula for the quartiles in particular and percentiles in general asks you to select the…

Can the standard deviation be more than half of the range?

*Blog post

Year 2007

Statistical theory

I was trying to work with some simple data sets to see how large I could make the standard deviation relative to the range. I know the standard deviation can never be larger…

Publication Bias references

*Blog post

Year 2004

Being updated

Here is a list of resources originally published in the category page of my old website. I want to restructure these and put them in separate pages with a common format.

When bad control groups happen to good researchers

*Blog post

Year 2007

Observational studies

Placebos in research

The Kansas City University of Medicine and Biosciences wants me to give a light humorous talk at lunch during the 2007 Homecoming CME and Reunion weekend. Somehow, they…

Use of diagnostic tests for making clinical decisions

*Blog post

Year 2007

Diagnostic testing

I’m giving a talk for the American College of Allergy, Asthma, and Immunology with the title “Use of diagnostic tests for making clinical decisions.” Here’s an abstract of…

Seven different formulas for the odds ratio

*Blog post

Year 2007

Writing research papers

I received an interesting email recently. Someone was studying the relationship between firearm suicides and veterans to answer the question: “Are veterans more likely to…

Seven different formulas for the odds ratio

*Blog post

Year 2007

Writing research papers

I received an interesting email recently. Someone was studying the relationship between firearm suicides and veterans to answer the question: “Are veterans more likely to…

Accounting for cyclical trends in a regression model

*Blog post

Year 2007

Linear regression

One of the doctors brought by a data set that showed the average volume of business (number of beds filled) in a month for 28 consecutive months starting in January 2005.…

Illustrated case studies of research ethics and research fraud

*Blog post

Year 2007

Ethics in research

I’ve written a fair number of case studies involving research ethics and research fraud for the Chance Wiki. I want to take some of this material and produce some web pages…

Centering the data

*Blog post

Year 2007

Data transformations

Why do we have to center the data before analyzing it? What would happen if we failed to center the data?*

Calculating probabilities involving correlated normal variables

*Blog post

Year 2007

Probability concepts

Someone on EDSTAT-L asked about a problem involving differences of independent normal random variables. I am simplifying the problem a bit, but it essentially asked a…

Applying likelihood ratios in your head

*Blog post

Year 2007

Diagnostic testing

Someone sent me a nice email complimenting my likelihood ratio slide rule.

Using real examples in teaching statistics (May 30, 2007)

*Blog post

Year 2007

Teaching resources

I am writing a book review and wanted to get some opinions from participants on EDSTAT-L about the tendency that this book (and many others) has for using hypothetical…

May has been a slow month

*Blog post

Year 2007

Website details

After a burst of activity, my work on the weblog has slowed down quite a bit this month. There are three reasons (excuses):

Classic references in evidence based medicine

*Blog post

Year 2007

Teaching resources

A couple of weeks ago, a regular correspondent (PG) on the Evidence Based Health email discussion group asked about what were the essential readings in Evidence Based…

Choosing between two conflicting analyses

*Blog post

Year 2007

Pvalues

Someone wrote in and asked about an analysis where there was only a limited amount of data. The simple analysis using an odds ratio produced a significant result (p=0.048).…

Where can you find interesting case studies in Statistics?

*Blog post

Year 2007

Teaching resources

Someone wrote in to the MedStats email discussion group and asked about where to find interesting articles with full free text and sufficient detail that students could…

What to measure in a post-marketing surveillance study

*Blog post

Year 2007

Clinical importance

I am volunteering as a data analyst in a post-marketing surveillance to assess the safety and efficacy of a drug. I’m not sure what to measure and how to measure it. Can you…

Cohen’s Kappa with small cell sizes

*Blog post

Year 2007

Measuring agreement

Small sample size issues

Someone on Edstat-L wrote in asking about using Cohen’ Kappa with a small sample size in some of the cells. Here’s an example:

ANOM table for alpha=0.05, part 2

*Blog post

Year 2007

Analysis of means

Here’s a table of critical values for analysis of means (ANOM) at an alpha level of 0.05. It is a continuation of the table

Fitting a beta binomial model using BUGS

*Blog post

Year 2007

Bayesian statistics

I’ve spent a bit of time trying to learn how to run a program called BUGS. The acronym stands for Bayes Using Gibbs Sampling. Here is my first serious attempt to run a BUGS…

A simple illustration of the Metropolis algorithm

*Blog post

Year 2007

Bayesian statistics

In many situations, you need to generate a random sample from a distribution that is rather complex. When simpler methods for generating a random sample don’t work, there…

Special section for quotations

*Blog post

Year 2007

Obsolete page

Website details

*Quotation

[Note: the organizational details of the current website differ from that described here.]

When I talk about statistics

*Quotation

Year 2007

Critical appraisal

When I talk to people about statistics, I find that they usually are quite willing to criticize dubious statistics–as long as the numbers come from people with whom they…

IRB review of studies with methodological flaws

*Blog post

Year 2007

Ethics in research

Someone (AK) wrote into the IRBForum asking about how the IRB should do when they discover methodological flaws in the proposed research. If everything else is in order…

Quantifying the ability of dreams to predict the future

*Blog post

Year 2007

Diagnostic testing

Someone wrote to me about a diary they had kept for the past eight years about their dreams. About every other month or so, a dream of theirs came true. I was asked if I…

One of the naturalists had argued that

*Quotation

Year 2007

Theory versus practice

One of the naturalists had argued that On the Origin of Species was too theoretical, that Darwin should have just “put his facts before us and let them rest.” In response…

What is an adequate sample size for establishing validity and reliability?

*Blog post

Year 2007

Measuring agreement

Sample size justification

Someone from Mumbai, India wrote in asking whether a sample of 163 was sufficiently large for a study of reliability and validity. This was for a project that was already…

Calculating rates

*Blog post

Year 2007

Poisson regression

Someone on the MedStats discussion group asked how to calculate a rate of needlestick incidents. The answer is quite simple, but there are a variety of possible responses.

What makes a good diagnostic test?

*Blog post

Year 2007

Diagnostic testing

I’ve been invited to give a talk at the annual meeting of the American College of Allergy, Asthma & Immunology. The tentative title of the talk is “What makes a good…

useR! 2007 conference in Ames, Iowa

*Blog post

Year 2007

R software

I may not be able to go to it, but the R community has an annual meeting, useR!, that will be held this year in Ames, Iowa from August 8-10. The web site for this conference (…

Tracking adverse events during kidney biopsy, Part 2

*Blog post

Year 2007

Adverse events

This is a major revision of a March 14, 2007 weblog entry.

Further explanation about Type I and Type II errors

*Blog post

Year 2007

Hypothesis testing

I got some feedback that my definitions of Type I > errors and Type II > errors would be > clearer if I specified what the actual hypothesis are. I wanted to > avoid symbols…

The Seven Deadly Sins of Researchers

*Blog post

Year 2007

Critical appraisal

I was reading an article in written by Steven Goodwin, The Seven Sins of Programmers, published in issue 17 of the Free Software Magazine and thought it would be fun to use…

Reporting data analysis on transformed data

*Blog post

Year 2007

Incomplete page

Statistical models

I’m confused by the use of transformations in Statistics. When you transform the data, the standard deviation is bound to be incorrect, even after you invert the…

R Wiki

*Blog post

Year 2007

R software

I use R software for a lot of my complex data analyses and have written up a few web pages about various things you can do with R. It turns out that R has a Wiki site, R Wiki

IRB review of a pilot study

*Blog post

Year 2007

Ethics in research

Pilot studies

Sample size justification

I am the new chair of the IRB at a county hospital. Many of the studies we review are pilot studies with small samples. I have been trying to locate criteria for the…

Confidence intervals for count data

*Blog post

Year 2007

Poisson regression

If you have data involving counts, you have several options for computing confidence intervals. All of these approaches rely on approximations to the Poisson distribution or…

Some UNIX humor

*Blog post

Year 2007

Statistical computing

The website www.netfunny.com has a lot of computer humor. Here’s one that caught my eye because I am taking a class in Bioinformatics and am learning a lot about UNIX.

Interpretation of an odds ratio

*Blog post

Year 2007

Logistic regression

Someone sent me some data on crime. In a sample of 2,957,239 people, 961 were criminals. 41 of the criminals were in the first group (who numbered 20,109). The remaining 920…

What I’m working on right now

*Blog post

Year 2007

Analysis of means

Bayesian statistics

Quality control

There are several research projects where I am actively looking for collaborators. I thought I’d outline these topics briefly here.

Randomly dividing a dataset in R

*Blog post

Year 2007

R software

I’m working with someone who wants to do a simple cross-validation of a statistcal procedure. One simple way to do this is to randomly divide a data set into two piece.…

Randomly dividing a dataset in R

*Blog post

Year 2007

R software

A regular contributor to EDSTAT-L (DR) mentioned the following interesting resource:

Bad calculation of annual rate of return

*Blog post

Year 2007

Wiki pages

The Chance Wiki has a section called “Forsooths.” This section presents quantitative errors in the popular press that are self-evident under careful examination. I found an…

Thanks to all my proofreaders!

*Blog post

Year 2007

Website details

Someone emailed me with a suggestion that I have said “increase” when I meant to say “decrease” and “decrease” when I meant to say “increase.” I looked at the page in…

Tracking adverse events during kidney biopsy

*Blog post

Year 2007

Adverse events

I have been helping a colleague who is interested in monitoring the safety of kidney biopsy events. He was kind enough to let me use his data set on my web pages in order to…

Ignore weak evidence at your own peril

*Blog post

Year 2007

Critical appraisal

I ran across an interesting article recently.

Reviewing a paper on qualitative data analysis

*Blog post

Year 2007

Qualitative research

I was asked by BMJ to review a paper that involved a qualitative data analysis. These reviews are confidential, so I don’t want to describe the paper in any detail. It is…

Manipulation of peer-review publications by pharmaceutical companies

*Blog post

Year 2007

Conflict of interest

This weblog entry provides some discussion points that I want to share in a seminar:

How to draw a fishbone diagram

*Blog post

Year 2007

Quality control

This is a condensed version of a handout

Calculating a P control chart

*Blog post

Year 2007

Broken link

Control charts

If you are collecting data on proportions with a consistent denominator for each proportion, then you can plot this data on a control chart. This type of chart is called a P…

P control chart, answers to on your own exercises

*Blog post

Year 2007

Control charts

On the web page Calculating a P control chart you were asked to calculate P charts for the following two data sets:

Analysis of Means answers to on your own exercises

*Blog post

Year 2007

Analysis of means

Incomplete page

On the web page

Calculation of Analysis of Means limits

*Blog post

Year 2007

Analysis of means

Incomplete page

This page shows some of the details for calculating an analysis of means (ANOM) chart.

Review of statistical methods in The New England Journal of Medicine and Nature Medicine

*Blog post

Year 2007

Human side of statistics

The Kansas University Medical Center has a statistics journal club and this month, they reviewed an article

ANOM table for alpha=0.05, part 1

*Blog post

Year 2007

Analysis of means

Incomplete page

Here’s a table of critical values for analysis of means (ANOM) at an alpha level of 0.05.

Handouts for quality control workshop

*Blog post

Year 2007

Quality control

I am in charge of a workshop for the American Society for Andrology for their 32nd Annual Conference in Tampa Florida. This society holds a laboratory workshop every year…

Analysis of Means calculations

*Blog post

Year 2007

Analysis of means

Incomplete page

Analysis of Means (ANOM) are available for a wide range of data sets, and it is impossible to summarize all the applications of ANOM here. The goal on this web page is to…

PharmedOUT website

*Recommendation

Year 2007

Conflict of interest

In response to educational resources in medicine that are dominated by drug company support, a new website, PharmedOUT, has been formed. This site is developed by Adriane…

Calculating an XBAR-S control chart

*Blog post

Year 2007

Control charts

The following data represents a weekly evaluation of vaccine potency. The data is taken from

XBAR-S control chart, answers to on your own exercise

*Blog post

Year 2007

Control charts

On the web page

Using a pocket calculator to compute a standard deviation

*Blog post

Year 2007

Descriptive statistics

Most of the time, I let a computer program like SPSS compute quantities for me, but every now and then, I want to calculate a few simple statistics without the benefit of…

Team exercise to illustrate ANOM calculations

*Blog post

Year 2007

Broken link

Analysis of means

I am in charge of a workshop for the American Society for Andrology for their 32nd Annual Conference in Tampa Florida. This society holds a laboratory workshop every year…

Stats

*Blog post

Year 2007

Being updated

Website details

Stats

*Blog post

Year 2007

Website details

Being updated

Stats

*Blog post

Year 2007

Website details

Formulas for cumulative Poisson and binomial probabilities

*Blog post

Year 2007

Poisson regression

Probability concepts

I am updating some material about Poisson regression and noticed that some of the tests and confidence intervals rely on a percentile from a Chi-squared distribution or a…

Searching through the Current Index to Statistics

*Blog post

Year 2007

Information searching

I wanted to search for any recent references about teaching Bayesian statistics. The American Statistical Association has a nice resource for its members, the Current Index…

Three simple rules to establish quality

*Blog post

Year 2007

Broken link

Quality control

I received a recommendation to purchase a book (Process Quality Control, by Ellis Ott) and while searching for reviews of this book, found something called Ott’s Rules.…

A recent contribution to Wikipedia and to the Chance Wiki

*Blog post

Year 2007

Wiki pages

I’ve made some minor contributions from time to time in Wikipedia, a free encyclopedia on the web edited by volunteers. My previous work was on

Watch out for ambiguous data

*Blog post

Year 2007

Data management

Someone brought me a data set with some interesting values. It serves as a good example about why you need to carefully review simple descriptive statistics before you…

Advice for searching in PubMed

*Blog post

Year 2007

Incomplete page

Information searching

Trish Greenhalgh wrote a nice article about searching for medical information using PubMed.

Compound interest and powers

*Blog post

Year 2007

Statistical theory

In some of my mathematical calculations, I end up computing an expression that involves a number very close to one raised to a very large power. This term can often be…

Resources for fMRI data analysis

*Blog post

Year 2007

Imaging

I was asked to provide feedback on a grant that will use functional magnetic resonance imaging (fMRI) as one component of the research. This technique is used to quantify…

When is a control chart not a control chart?

*Blog post

Year 2007

Analysis of means

Control charts

Incomplete page

I found a pair of data sets on the web that represent counts and where one goal of the data collection is to see if any of the individual counts differ from the overall…

Modular arithmetic and rounding in R

*Blog post

Year 2007

R software

In certain programming situations, you need to perform calculations involving division that produce whole numbers as a result. For example, if you divided 27 by 4, you would…

The danger of providing expert testimony when you are not an expert

*Blog post

Year 2007

Human side of statistics

Sir Roy Meadow is an expert on child abuse, having published a landmark paper in 1977 on a condition known as Munchausen Syndrome by Proxy. An observation of his

Not everything that can be counted

*Quotation

Year 2007

Qualitative research

Not everything that can be counted counts, and not everything that counts can be counted. - Albert Einstein (1879-1955). Quote found in the January 31, 2006 issue of WXPnews.

Do your own power and sample size calculations

*Blog post

Year 2007

Sample size justification

Someone asked me for some power calculations and the problem was stated very tersely and completely.

Fitting a difference in exponential functions

*Blog post

Year 2007

Nonlinear regression

I was presented with a data set of sixteen subjects that showed a rise in values from zero to a maximum followed by gradual return of those values to zero for each subject.…

Manipulating graphic images using a touchscreen interface

*Blog post

Year 2007

Statistical computing

There is a cute video out showing some examples of manipulating graphic images using a touchscreen interface. In particular, the operator can expand images and zoom in by…

Books that discuss Poisson regression

*Blog post

Year 2007

Poisson regression

Someone on the MedStats discussion group asked about books discussing Poisson regression. If you want to use Poisson regression, you need an overview of the generalized…

Tests of hypothesis and confidence intervals involving a correlation coefficient

*Blog post

Year 2007

Linear regression

Suppose you compute a correlation coefficient from a sample of patients. Can you test a hypothesis about this correlation? Can you place confidence limits around this…

Technometrics review of Statistical Evidence

*Blog post

Year 2007

Professional details

The February 2007 issue of Technometrics has a review of my book, Statistical Evidence in Medical Trials. The review is not available on the web, unless you subscribe to…

Resources describing biplots

*Blog post

Year 2007

Categorical data

I’ve written some code in R to present a graphical summary of a complex data set using biplots. I write most of the code myself using the singular value decomposition…

What can you do with 100 words?

*Blog post

Year 2007

Wiki pages

I added another short entry to Chance News 23 about a dubious claim that 100 words are needed for half of all reading in English.

Differences between the Chi-square test, Fisher’s Exact test, and logistic regression

*Blog post

Year 2007

Logistic regression

I received an email from India (isn’t the Internet wonderful?) that asked me to comment on the differences between a Chi-square test, Fisher’s Exact test, and logistic…

Can Google replace your doctor?

*Blog post

Year 2007

Diagnostic testing

An article published in BMJ argues that Google searches can sometimes aid with developing an appropriate diagnosis of disease.

Variable cluster sizes and their impact on sample size calculations

*Blog post

Year 2007

Sample size justification

A recently published article in the International Journal of Epidemiology discusses sample size requirements for cluster randomized trials when the size of the cluster…

Be sure to account for dropouts in your sample size calculation

*Blog post

Year 2006

Sample size justification

I helped out a colleague with an NIH grant, and when the critique came back, it mentioned two issues that I should have been aware of. First, they pointed out the need for…

What percentage of medical decisions are based on good evidence?

*Blog post

Year 2006

Teaching resources

A correspondent on the evidence based health list noted a commonly quoted statistic that only 10% of all medical practices are based on solid evidence (e.g., randomized…

Cherry picking the literature

*Blog post

Year 2006

Systematic overviews

I have a relative who loves to send me articles supporting a particular religious and political viewpoint that he endorses. While that viewpoint he espouses is usually…

Unusual advice about control charts

*Blog post

Year 2006

Control charts

Someone sent me some recommended guidance on how to use a control chart and it included the following quote:

Using focus groups to bridge the gap between research and practice

*Blog post

Year 2006

Qualitative research

The Injury Prevention journal published a nice article on how to use focus groups to bridge the research-practice gap,

Should/Can Statistical Consultants, be Independent?

*Blog post

Year 2006

Human side of statistics

I attended a webinar, “Should (Can?) Statistical Consultants, be Independent?” presented by Janet Wittes.

Mathematical and statistical challenges

*Blog post

Year 2006

Statistical theory

A regular poster on the EDSTAT-L list (DR) mentioned an interesting page on the IBM website, www.research.ibm.com/ponder, that offers a monthly puzzle on mathematical…

Evidence-based development of medical guidelines

*Blog post

Year 2006

Teaching resources

An open source journal, Health Research Policy and Systems, has a series of articles on how to develop guidelines in a rigorous and evidence-base manner. Here are the first…

Perfect isn’t quite good enough

*Blog post

Year 2006

Small sample size issues

Someone wanted me to double check their calculations for Fisher’s Exact test. If the control group, 3 out of 10 patients experienced an unfortunate outcome. In the treatment…

PharmaIQ talks

*Blog post

Year 2006

Data mining

I attended the conference “Signal Detection and Data Mining” sponsored by PharmaIQ. Here are some notes I took during some of the talks.

When are two events worrisome?

*Blog post

Year 2006

Early stopping

I was attending a workshop on developing a risk management plan for a new drug. The presenter, Nawab Qizilbash from Oxon Clinical Epidemiology, gave an interesting example.…

Manipulation of peer-review publications by pharmaceutical companies

*Blog post

Year 2006

Ethics in research

I volunteered to give a talk at a local hospital, and the topic I’d like to discuss is “Manipulation of peer-review publications by pharmaceutical companies.” It would cover…

A simple Bayesian model for accrual

*Blog post

Year 2006

Accrual problems

Bayesian statistics

Rmarkdown code

Suppose you are a researcher in charge of a long term study. You plan to collect data on 120 patients. The goal is to finish your study in ten years, which means getting 12…

The tension between scientific validity and ethical concerns

*Blog post

Year 2006

Placebos in research

A question on the IRB Forum email discussion group (from RI) centered on the ethical concerns about using a placebo arm in a study involving control of pain. There are…

Fitting a quadratic regression model

*Blog post

Year 2006

Linear regression

Someone came in asking about how to examine for non-linear relationships among variables. In particular, they wanted to look for a U-shaped pattern where a little bit of…

The complexities of having a variable number of measures per patient

*Blog post

Year 2006

Multilevel models

A series of messages on the MedStats email discussion group emphasized the difficulty in analyzing data where subjects contribute a variable number of measurements to the…

The danger of using humor on a web page

*Blog post

Year 2006

Website details

I got a nice email yesterday from someone who had read my web page with a definition of a retrospective study.

Incorporating risk factors into diagnostic test calculations

*Blog post

Year 2006

Diagnostic testing

A contributor to the Evidence-Based Health email discussion group (PK) raised an interesting question about how to incorporate information about risk factors when applying…

Technical Articles and Reports by David Heiser

*Recommendation

Year 2006

Statistical computing

David A. Heiser, a regular contributor to EDSTAT-L, has a nice web page at that covers some of the numerical accuracy and computational problems inherent in many statistical…

Rebutting an expert reviewer

*Blog post

Year 2006

Human side of statistics

A regular contributor to EDSTAT-L (KW) asked about how to handle a bad peer review of an article that a colleague had submitted. The reviewer appeared to get the definitions…

Materials for Signal Detection and Data Mining Strategies conference

*Blog post

Year 2006

Administrative details

I had a November 6 deadline to send materials to PhamaIQ for the two talks I am giving at the Signal Detection and Data Mining Strategies conference being held in London…

Medline is a very busy place

*Blog post

Year 2006

Information searching

According to a National Library of Medicine announcement

Additions and improvements to my web pages

*Blog post

Year 2006

Broken link

Obsolete page

Website details

Sample size justification

This page is obsolete. I am keeping it around for nostalgic reasons. Some of the links on this page are broken and I will try to fix them when I have time.

Statistical concerns in research studies involving children

*Blog post

Year 2006

Children in research

The statistical design and analysis issues for research involving children are not really that much different than for adults, but there are three areas that you need to pay…

Parametric tests for a ratio

*Blog post

Year 2006

Unusual data

Dear Professor Mean, I computed a variable, Y3, which is the ratio of two other variables, Y1 and Y2. Can I use a parametric test on this ratio?

Adjusting a variable for age and sex

*Blog post

Year 2006

Covariate adjustment

Someone asked me how to adjust bone mineral density (BMD) for age and sex. I presume that BMD changes as children grow (or as adults age) and that BMD is different for men…

Searching for pediatric articles on Medline

*Blog post

Year 2006

Children in research

Information searching

A recent publication

Is a 10% shortfall in sample size critical?

*Blog post

Year 2006

Confidence intervals

Sample size justification

Dear Professor Mean, I’m reviewing a paper where they did a power calculation based on 60 patients per group, but in the research study, they ended up only getting 55/58 per…

A simple example of a mixed linear regression model

*Blog post

Year 2006

Multilevel models

I want to illustrate how to run a simple mixed linear regression model in SPSS. I will use some data on the plasma protein levels of turtles at baseline, after fasting 10…

Ethical concerns about research in children

*Blog post

Year 2006

Children in research

Pediatric research must balance two important social and ethical goals. First, scientific progress that includes issues important to children will by necessity require that…

Case studies for differences in research in children

*Blog post

Year 2006

Children in research

I want to include several case studies about issues relating to the differences in research in children. Here are some articles with full free text on the web which I think…

Mathematical derivation of the odds form of Bayes theorem

*Blog post

Year 2006

Diagnostic testing

I had included some rather technical details on my web page about likelihood ratios, but I thought it would be best to move it to a separate page. Define the following terms:

Differences between children and adults

*Blog post

Year 2006

Children in research

A recently published report from the Institute of Medicine, Emergency Care for Children--Growing Pains, has a very nice table in the introduction that highlights some of the…

Frank Harrell’s Philosophy of Biostatistics

*Blog post

Year 2006

Modeling issues

There are a lot of people in the world who are a lot smarter than I am and it is always a humbling experience when I recognize how little I really know.

Book reviews for Statistical Evidence

*Blog post

Year 2006

Statistical evidence book

The International Journal of Epidemiology published a review of my book, Statistical Evidence in Medical Trials, in their September 15, 2006 issue. You need to be a…

My second grant, part 3

*Blog post

Year 2006

Accrual problems

I just finished my second grant, which I gave the title “Estimating delays in completion of IRB approved and KBR supported research studies” The two acronyms, IRB and KBR…

Improvements to weblog categories

*Blog post

Year 2006

Website details

With over a thousand web pages, I need a good way of letting people find related topics on my website. I’ve added categories to my weblog entries, and now I want to link…

Is my confidence interval too wide?

*Blog post

Year 2006

Clinical importance

Confidence intervals

Dear Professor Mean, Is there a rule of the thumb to judge if a 95% CI is wide or narrow?

I tell a story about a researcher who gets a six year, ten million dollar NIH…

Two talks for PharmaIQ

*Blog post

Year 2006

Children in research

I may be giving a couple of talks for for PharmaIQ, a division of the International Quality & Productivity Center (IQPC). The first has the title “Signal Detection…

Oops! I found statistical significance in my pilot study

*Blog post

Year 2006

Early stopping

Dear Professor Mean, I ran a pilot study to help me estimate the sample size for a larger study. There were 15 patients in each arm of the pilot, and when I analyzed the…

Special issues for research involving children

*Blog post

Year 2006

Ethics in research

Research is difficult enough, but it becomes more difficult when the research involves children. The issues that you need to consider are physiologic, ethical, and…

Resources for the use of Statistical Process Control in Healthcare

*Blog post

Year 2006

Quality control

Someone on the MedStats email discussion group asked for resources that “explain the use of SPC (statistical process control) to analyze quality indicators in a healthcare…

Pharmacogenetics Research Network

*Blog post

Year 2006

Genetic data analysis

I received an email today discussing a special conference being held by the the Pharmacogenetics Research Network (PGRN). It’s an “invitation only” conference, so I must…

Ambiguous nature of the word “risk”

*Blog post

Year 2006

Critical appraisal

A recent discussion on the Evidence-Based Health email discussion group focused on the word “risk”. It means harmful event (risks versus benefits) as well as a probability…

Email discussion groups

*Blog post

Year 2006

Teaching resources

An email discussion group is a collection of individuals with a common interest who supply their email address to a common site, typically called a listserver. When…

My second grant, part 2

*Blog post

Year 2006

Accrual problems

I took a three day workshop on grant writing and prepared a draft grant as part of the student exercises in that class. It’s not in the format that I need to use, but it…

Graphics options in R

*Blog post

Year 2006

Graphical display

R software

When you are producing graphics in R, the default option does not save your graphs for later review. You can change this in several ways. My comments will discuss the…

Postmodern thought and evidence based medicine

*Blog post

Year 2006

Teaching resources

A recently published article:

Rules for rounding numbers

*Blog post

Year 2006

Descriptive statistics

When you are reporting means and percentages from a descriptive data analysis, you should round your data to make it more readable. Ideally, you should show only two…

Continuous monitoring of the number needed to harm

*Blog post

Year 2006

Adverse events

The continuing review of clinical trials has to address “good news” issues. Does one arm of the study show substantially better efficacy? Does one arm of the study have a…

Changing page breaks in SPSS

*Blog post

Year 2006

SPSS software

SPSS often chooses some unusual and unfortunate places to make a page break. You can fix this, according to a helpful soul on the SPSSX-L listserv (MG). Just tell SPSS never…

Wikipedia entry on Binomial Confidence Interval, Part 3

*Blog post

Year 2006

Wiki pages

Here’s some additional material that I will add to the Wikipedia entry on Binomial Proportion Confidence Interval.

Citing statistical software in research papers

*Blog post

Year 2006

Statistical computing

On of the most common questions I get is how to properly acknowledge the use of a program like SPSS in a research publication. In a series of messages in the MedStats discuss…

Wikipedia entry on Binomial Confidence Interval, Part 2

*Blog post

Year 2006

Wiki pages

Here’s my first attempt to improve the Wikipedia entry on the binomial confidence interval. I start by simplifying and improving the introduction

Quality control humor

*Blog post

Year 2006

Quality control

It is important in any quality improvement process to define precisely what it is that you are trying to improve. Sloppy and imprecise definitions will make it hard for you…

An exact confidence interval for a binomial proportion

*Blog post

Year 2006

Confidence intervals

A researcher came into my office this morning with some data that was strongly negative. Out of 15 patients, none showed a detectable improvement after the use of a…

More than one thousand web pages now available on my site

*Blog post

Year 2006

Website details

When you do a global search and replace in Frontpage, it offers a page count of all the pages that it searches. Sometime in the past month, I exceeded one thousand pages.…

American Statistical Association Traveling Course committee

*Blog post

Year 2006

Professional details

I volunteered to be the new chair of the Traveling Course committee of the American Statistical Association (ASA). The ASA recruits speakers who offer a one day course on an…

When should you worry about recall bias?

*Blog post

Year 2006

Observational studies

Dear Professor Mean, I am studying reports of early health concerns in a group of children with a chronic disease compared to a matched group of healthy controls. I believe…

Sales figures for Statistical Evidence in Medical Trials

*Blog post

Year 2006

Statistical evidence book

I get twice yearly data on sales, and the first of these arrived today. I’ve sold 230 copies, which is not bad for a short time frame. I updated my page on the book and…

To be updated

*Blog post

Year 2008

Being updated

Statistical evidence book

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

R libraries for sample size justification

*Blog post

Year 2006

R software

Sample size justification

There are a lot of good commercial and free sources for sample size justification. Note that most people use the term power calculation, but there is more than one way to…

My second grant

*Blog post

Year 2006

Accrual problems

I’m in the final stretch of writing a grant to submit to the Kansas City Area Life Sciences Institute.

Using a colloquial tone in a grant application

*Blog post

Year 2006

Grant writing

As I have mentioned many times in this weblog, I am writing a grant. A rough draft of the grant is available in PDF format. If you have feedback, I’d love to hear it by…

Selecting randomly from a list

*Blog post

Year 2006

Randomization

A common task in research is to randomly select a subgroup from a list. For example, you have the names of 26 patients, Alpha, Bravo, Charlie, Delta, etc. Suppose you want…

Questions a volunteer should ask before participating in a clinical trial

*Blog post

Year 2006

Ethics in research

A regular contributor to the IRBForum (MG), wrote a nice list of questions that a volunteer should ask before they decide to participate in a clinical trial.

Seminar notes. Missing values in a dose response model

*Blog post

Year 2006

Nonlinear regression

One of the talks at the 18th Annual Applied Statistics in Agriculture Conference, sponsored by Kansas State University was “Dose-Response Modeling with Marginal Information…

Seminar notes. Issues in the analysis of mixed linear models

*Blog post

Year 2006

Multilevel models

The keynote address at the 18th Annual Applied Statistics in Agriculture Conference, sponsored by Kansas State University was “Random Observations with Mixed Feelings”…

Seminar notes. Working with molecular biologists

*Blog post

Year 2006

Human side of statistics

One of the talks at the 18th Annual Applied Statistics in Agriculture Conference, sponsored by Kansas State University was “A visual aid to help a statistician work with a…

Seminar notes. Adjustments for multiple comparisons

*Blog post

Year 2006

Analysis of variance

One of the talks at the 18th Annual Applied Statistics in Agriculture Conference, sponsored by Kansas State University was “A Comparison of Multiple Tests Procedures…

Fraudulent images in research

*Blog post

Year 2006

Ethics in research

Fraud in research is a big problem. One issue that has come up recently is that graphical images can be “Photoshopped” to present the image in a way that does not truly…

When can a conservative trust a liberal information source (and vice versa)

*Blog post

Year 2006

Conflict of interest

I have a brother-in-law who loves to debate politics and religion. He always takes an aggressively conservative stand (I’m a flaming liberal, but try not to mention politics…

Possible sources of funding for my grant

*Blog post

Year 2006

Accrual problems

The NIH has a Request for Application (RFA) titled Research on Research Integrity (R01). The full text of this announcement is on the web at

Stopping rules for a Data Safety Monitoring Plan

*Blog post

Year 2006

Early stopping

If a research study requires a DSMP (Data Safety Monitoring Plan), that plan should outline conditions that would cause a study to end early. It is difficult to specify what…

Some resources for Analysis of Means

*Blog post

Year 2006

Analysis of means

One of the techniques recommended by Davis Balestracci when he visited CMH in June 2006 was Analysis of Means, which often is abbreviated ANOM. You can use ANOM much like a…

What is block randomization

*Blog post

Year 2006

Randomization

Several people have asked me about block randomization, and while I discuss it briefly on several of my web pages, there is a better definition on the Consort Statement web…

Likelihood software for clinical trials

*Blog post

Year 2006

Statistical computing

A member of our local IRB forwarded a press release announcing new software that would revolutionize the conduct of clinical trials. The company is called Analytical Edge…

The problem with ranking ordinal scales

*Blog post

Year 2006

Unusual data

When I was young and naive, I thought that anytime you encountered ordinal data, it would make the most sense to use a test statistic based on ranks, such as the…

Colors for R graphs

*Blog post

Year 2006

Graphical display

R software

I tend to use color sparingly in graphs because most of my graphs end up in black and white in the final production. Even on my web pages - which appear in color - I try to…

Resources for Item Response Theory

*Blog post

Year 2006

Statistical computing

One area that I would like to investigate when I have time is Item Response Theory (IRT). This is an approach that is sometimes called a latent trait model or a Rasch model…

Slash and burn models

*Blog post

Year 2006

Modeling issues

I received an email question about developing a logistic regression model with some interaction terms. One of the interaction terms was statistically significant but one or…

Using a charge of fraud to achieve a political end

*Blog post

Year 2006

Ethics in research

There was an interesting paper published recently:

Applications of the CUSUM chart

*Blog post

Year 2006

Accrual problems

Control charts

I am interested in investigating the use of CUSUM charts in monitoring accrual rates, drop out rates, and adverse event rates in a clinical trial. Some references which I…

Auditing for data entry errors

*Blog post

Year 2006

Data management

There was an interesting query on the MedStats list about the appropriate sample size for an audit. This person had entered 1,500 records and wanted to check a sample of…

Putting a human face on Evidence Based Medicine

*Blog post

Year 2006

Teaching resources

A correspondent (BD) on the Evidence Based Health email discussion group pointed out the following web site:

Philosophy of teaching

*Blog post

Year 2006

Teaching resources

The email discussion group, EDSTAT-L, has had an extended discussion of teaching philosophy. I do some teaching myself, and I must admit that I don’t think nearly enough…

Withholding Personal Health Information from a patient

*Blog post

Year 2006

Privacy in research

An interesting discussion on the IRBForum related to a statement in an informed consent document that informed the patient that PHI (Personal Health Information) would be…

Seminar notes. Confidence intervals for a variance ratio

*Blog post

Year 2006

Analysis of variance

One of the talks at the 18th Annual Applied Statistics in Agriculture Conference, sponsored by Kansas State University was “Selecting the Best Confidence Interval for a…

New entry in the Chance Wiki

*Blog post

Year 2006

Wiki pages

I just posted a new article in the Chance Wiki:

Seminar on control charts and adverse events

*Blog post

Year 2006

Accrual problems

I took some time to expand my May 30, 2005 weblog entry on accrual rates and developed a seminar which I will present to the Statistics journal club at KUMC today.The handout…

An amusing correlation

*Blog post

Year 2006

Linear regression

I always like simple amusing examples that illustrate an important statistical point. An email by JW on EDSTAT-L offer a couple of examples.

Methods for haplotype analysis

*Blog post

Year 2006

Genetic analysis

I am not an expert on haplotype analysis, but as I understand it, a haplotype is a combination of several SNPs (Single Nucleotide Polymorphisms) that show a stronger…

Monitoring accrual rates

*Blog post

Year 2006

Accrual problems

This scenario is based on real data, but has been adapted slightly to serve as an illustration of the use of control charts in monitoring a clinical trial.

Interesting stuff for the month of May

*Blog post

Year 2006

Interesting stuff

Interesting quotes

Note: any quotations on this page have been moved to Category: Interesting quotes.

Relationship between the standard deviation and the sample size

*Blog post

Year 2006

Descriptive statistics

Dear Professor Mean, I have a data set that is accumulating more information over time. When I estimate the standard deviation for one of the outcomes in this data set…

Upcoming talks about control charts

*Blog post

Year 2006

Adverse events

I am working on some ideas for a grant to use control charts to track adverse events in clinical trials. I also envision the possibility of using control charts as a warning…

Using APR-DRGs for risk adjustment

*Blog post

Year 2006

Covariate adjustment

The 3M company, famous for Post-It notes, among other things, has a division for health information systems. One of their products is software that produces classifications…

You won’t have Steve Simon to kick around anymore

*Blog post

Year 2006

Professional details

The results of the election of officers for the American Statistical Association came out today, and sad to say, I came in second in a two person race. I was running for…

Lost files

*Blog post

Year 2006

Data management

I work on these web pages from my desktop computer and two different laptop computers. I also have an Administrative Assistant who will sometimes update my web pages from…

Can the p-value actually equal 1.0?

*Blog post

Year 2006

Pvalues

Dear Professor Mean, I have a data set that compares the proportions in two groups. In the first group, the proportion is 19% (5/26). In the second group, the proportion is…

Another regular expression tip

*Blog post

Year 2006

Data management

I had a large text file and I had to find the first example of a line that did NOT begin with the letter A. That’s easier said than done, but you can use some special…

Using regular expressions to insert line breaks

*Blog post

Year 2006

Data management

I had to change a file written in XML format. The file was pretty easy to manipulate except that it had no line breaks in it. It was a single line of text with a length of…

Searching high level sources first

*Blog post

Year 2006

Information searching

When you have to perform a search for the evidence, it pays to look at high level sources first. A recent discussion on the Evidence Based Health mailing list produced a…

Using a web site to promote your book

*Blog post

Year 2006

Statistical evidence book

Someone on the MedStats email discussion group asked about how you use a web page to provide things like

Always ask why

*Blog post

Year 2006

Human side of statistics

I have a three year old boy at home and he’s learned that one way to keep the conversation going with an adult is to simply ask the question, “Why?”

What constitutes a conflict of interest?

*Blog post

Year 2006

Conflict of interest

I am a member of a committee that helps researchers set up Data Safety and Monitoring Boards (DSMBs) for research projects at Kansas University Medical Center (KUMC). The…

Data mining and drug safety

*Blog post

Year 2006

Adverse events

I am very interested in safety issues, especially in the continuing review/interim analysis of clinical trials. It turns out that S-plus is targeting drug safety as a…

A simple application of propensity scores

*Blog post

Year 2006

Covariate adjustment

In many research studies, you do not have the opportunity to randomly assign an exposure variable. The influence of the exposure variable on the outcome variable can…

Surviving Statistical Spitting Matches

*Blog post

Year 2006

Human side of statistics

I generally dislike an outline or bullet format for presenting information, but I came across a website

Abstainer errors in study of alcohol abuse

*Blog post

Year 2006

Diagnostic testing

Observational studies

A correspondent in the MedStats email discussion group (RR), mentioned an interesting example of problems in defining groups in observational studies. The actual publication…

Giving credit where credit is due

*Blog post

Year 2006

Website details

A lot of the material that I present on these web pages comes from reading various email discussion groups. I normally try to put in a plug for the groups when I can, but I…

Univariate Model Based Clustering

*Blog post

Year 2006

Cluster analysis

Back in 2001, I attended an excellent short course on a new approach to cluster analysis taught by Adrian Raftery and Chris Fraley at the Joint Statistics Meetings. Their…

Blindfolded Donkey

*Blog post

Year 2006

Outliers

Statistical koans

Earlier versions are here and here.

The Busy Tailor

*Blog post

Year 2006

Quality improvement

Statistical koans

Earlier versions are here and here.

Three new koans

*Blog post

Year 2006

Teaching resources

Over the weekend, I wrote three new koans.

Ninety Nine Samples

*Blog post

Year 2006

Confidence intervals

Statistical koans

Earlier versions are here and here.

The Only True Path

*Blog post

Year 2006

Randomization in research

Statistical koans

Earlier versions are here and here.

Topic list is complete!

*Blog post

Year 2006

Website details

It took a while, but I produced a topic list for every entry in my weblog. I may change some of these topics from time to time. The biggest advantage of placing a topic on…

Useless Gifts

*Blog post

Year 2006

Confidence intervals

Statistical koans

Earlier versions are here and here.

*Blog post

Year 2006

Hypothesis testing

Statistical koans

Earlier versions are here and here.

Wax Fruit

*Blog post

Year 2006

Confidence intervals

Statistical koans

Earlier versions are here and here.

Placing the symbol X-bar in a document

*Blog post

Year 2006

Teaching resources

Someone asked me how to place the symbol X-bar into a word processing document. This is tricky to do because there is nothing in the Symbol font that works and most word…

Interesting websites, publications and quotes for the month of April

*Blog post

Year 2006

Interesting stuff

Interesting quotes

Note: any quotations on this page have been moved to Category: Interesting quotes.

The Healthcare Cost and Utilization Project

*Blog post

Year 2006

Secondary data analysis

On April 20, I will be attending a webcast sponsored by the Agency for Healthcare Research and Quality (AHRQ) on a large data set they collected, the Healthcare Cost and…

What is a beta coefficient?

*Blog post

Year 2006

Linear regression

When you are examining the relative impact of several independent variables on an outcome variable, the estimated slopes may be deceptive. A variable with a wide range might…

When is a co-authorship warranted?

*Blog post

Year 2006

Human side of statistics

I am co-author on over 60 papers and have helped with the publication of many more papers. What does it take to get a co-authorship? I don’t quibble a lot about this, but it…

Can you use the coefficient of determination for categorical variables?

*Blog post

Year 2006

Linear regression

Dear Professor Mean, How can you compute a coefficient of determination (R squared) for a model that has a dichotomous variable? I thought that you could only compute this…

Interpretation of the correlation coefficient

*Blog post

Year 2006

Linear regression

There are many “rules of thumb” about how to interpret a correlation coefficient. They vary slightly from one to another, but all say about the same thing. Here’s a couple…

Articles on Bayesian data analysis

*Blog post

Year 2006

Bayesian statistics

Bayesian statistics

The Journal of Data Science has a couple of interesting Bayesian papers in the April 2006 issue.

Contradictory research

*Blog post

Year 2006

Critical appraisal

The Washington Post published an article that gets to the heart of the difficulty with Evidence Based Medicine. The URLs for these newspaper sites are always a bit…

How many charts should I pull?

*Blog post

Year 2006

Sample size justification

I got a question from someone doing a quality review. She needs to pull a certain number of medical records out of 892 and see whether the doctors followed the clinical…

The role of a statistician on an IRB

*Blog post

Year 2006

Human side of statistics

Someone on the IRBForum wrote in and asked what guidance their IRB could offer to a statistician who was just assigned to an Institutional Review Board (IRB). There were…

New koan page

*Blog post

Year 2006

Website details

I have consolidated the four statistical koans on a new page:

Proper treatment will cure a cold in seven days, but

*Quotation

Year 2006

Evidence Based Medicine

Proper treatment will cure a cold in seven days, but left to itself a cold will hang on for a week. Henry G. Felsen, as quoted in E. S. Roach. Complementary and alternative…

Small sample size, yet again

*Blog post

Year 2006

Small sample size issues

Dear Professor Mean, Is there any statistical test/method that will allow you to make statistically significant conclusions from a sample of nine? Someone was trying to tell…

Statistical koan #4

*Blog post

Year 2006

Teaching resources

A visit from a thief.

Seminar notes, Creating More Effective Graphics

*Blog post

Year 2006

Descriptive statistics

I attended a web seminar, “Creating More Effective Graphs,” taught by Michael O’Connell and Naomi Robbins and sponsored by Insightful Software, the makers of S-plus.

Examples of a fishbone diagram

*Blog post

Year 2006

Quality improvement

This page is obsolete. Please see http://www.pmean.com/06/fishbone.html.

My ten favorite books, #10

*Blog post

Year 2006

Good books

A recently purchased book is worth mentioning, and it will probably make my Top Ten list. It has a very good section on how to properly apply diagnostic tests in the real…

Crash Course in Spss for Windows

*Blog post

Year 2006

Interesting books

SPSS software

Crash Course in Spss for Windows: Updated for Versions 10, 11, 12 And 13. (2006-03-16) Andrew M. Colman, Briony Pulford. ISBN: 1405145315 Publisher: Blackwell Publishers -…

Statistical koan #3

*Blog post

Year 2006

Teaching resources

The blindfolded donkey.

Post hoc comparisons

*Blog post

Year 2006

Analysis of variance

Note: It’s been a while since I last used the “Ask Professor Mean” format on these web pages, and I can’t think of a good reason why I abandoned that format. I just saw a…

To be updated

*Blog post

Year 2008

Being updated

Statistical evidence book

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Software for structural equations models

*Blog post

Year 2006

Statistical computing

A recent email on the Medstats discussion group discussed software for structural equations models. Some of the packages mentioned were:

More on the Emily Rosa experiment

*Blog post

Year 2006

Critical appraisal

One of the more interesting research studies from an Evidence-Based Medicine perspective started out as a simple science fair project by a fourth grade student. Emily Rosa…

Poisson regression? Maybe not!

*Blog post

Year 2006

Poisson regression

I get a lot of questions about Poisson regression, even though I have very little about it on my web pages. My guess is that there is even less information out there on the…

Propensity scores

*Blog post

Year 2006

Covariate adjustment

When I have time, I want to describe the use of propensity scores and show some examples. Propensity scores offer a simple and effective way to correct for covariate…

What is construct validity?

*Blog post

Year 2006

Measuring agreement

Someone asked me to define face validity, criterion validity, and construct validity. That’s a tall order. In general, validity means that a measurement that we take…

To be updated

*Blog post

Year 2008

Being updated

Statistical evidence book

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Best EBM articles in 2005

*Blog post

Year 2006

Teaching resources

One of the regular contributors to the Evidence Based Health email discussion group asked what we felt were the Best EBM methods papers in 2005. I’ll report on the articles…

Update on my book, Statistical Evidence in Medical Trials

*Blog post

Year 2006

Statistical evidence book

Although I was expecting my book to appear sometime in February, a quick search of the Internet shows that March 31, 2006 may be a more realistic publication date. I have an…

To be updated

*Blog post

Year 2008

Being updated

Statistical evidence book

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Statistical koan #2

*Blog post

Year 2006

Teaching resources

I got some limited feedback from EDSTAT-L about using koans to illustrate difficult and subtle statistical concepts, and at least one person thought that this device would…

Statistical koans

*Blog post

Year 2006

Teaching resources

Update: Check out my koan page.

Difficulties in generalizing

*Blog post

Year 2008

Being updated

Extrapolations in research

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Difficulties in generalizing research

*Blog post

Year 2006

Extrapolations in research

I found this information thanks to an email in the Evidence-Based Health email discussion group. Someone asked if there was any empirical evidence that the setting of a…

Meta-analysis and diagnostic tests

*Blog post

Year 2006

Systematic overviews

I will be giving a talk at the graduate seminar series for the department of Mathematics and Statistics at UMKC on February 23. It will be a combination of material from the…

Checking a Chi-square test

*Blog post

Year 2006

Logistic regression

Someone preparing a critique of a research article wanted to check the accuracy of the statistics in that article. They noted that in a group of 37 patients without the…

What makes a good book? A sense of humor.

*Blog post

Year 2006

Good books

I was recently asked to evaluate a book proposal, and although I have not finished it, it made me think about what makes a book good. There are several things that I look…

Reporting serious adverse events

*Blog post

Year 2006

Adverse events

The FDA held a meeting on March 21, 2005 soliciting opinions about how adverse events should be reported to Institutional Review Boards (IRBs).

Learning more about control charts

*Blog post

Year 2006

Control charts

Someone asked me about resources for learning how to use control charts. I have a web page that talks about quality control in general and shows some of the computational…

An Ensembl search

*Blog post

Year 2006

Microarray analysis

While working on a microarray experiement with a researcher, we had to find a bit of information about a gene with the gene symbol NCOA3. We went to the Ensembl web site (www…

How do the various clustering algorithms work?

*Blog post

Year 2006

Cluster analysis

I’m working with someone on some clustering models for his microarray experiment. He asked how the various clustering algorithms work.

More lessons learned the hard way

*Blog post

Year 2006

Data management

The more I do, the more I realize how little I have thought about how to properly conduct a statistical analysis. One lesson I thought I had learned was that it costs next…

Recent developments in searching for evidence

*Blog post

Year 2006

Information searching

Dean Giustini publishes a web log, the UBC Google Scholar Blog, that covers recent developments and improvements in searching for evidence.

Real-life examples of survey mistakes

*Blog post

Year 2006

Survey design

Tzippy Shocat was nice enough to forward a link to an article that she wrote for the iSixSigma website (www.isixsigma.com), titled “Tips for Getting the Most from Six Sigma…

A simple function for a Biplot in R

*Blog post

Year 2006

Data mining

I regularly use a biplot or principal components plot as an initial exploratory tool for microarray analyses, but I have not found a good package that does this for me…

Machine Learning tools in R

*Blog post

Year 2006

Data science

R software

There are a variety of different models that perform supervised learning or classification problems

Randomization tests for paired data

*Blog post

Year 2006

Unusual data

The randomization test offers a lot of flexibility for analyzing data in ways well beyond what traditional tests might offer. The concept is quite simple. Suppose that you…

Multicollinearity is not a violation of assumptions

*Blog post

Year 2006

Modeling issues

A colleague from my days at the National Institute for Occupational Safety and Health emailed me a question. Apparently, one of the co-authors of a paper he is writing is in…

Davis Balestracci seminar

*Blog post

Year 2006

Quality control

A couple of people I work with are very interested in applying quality control in various processes at Children’s Mercy Hospital. We already have a quality improvement…

Excluding zip codes with insufficient data

*Blog post

Year 2006

Descriptive statistics

Someone asked about a study evaluating rates of children with tooth decay according to the zip code they live in. Some zip codes might have hundreds of children evaluated…

Categorizing my weblog entries

*Blog post

Year 2006

Website details

It’s probably a sign of lack of discipline on my part, but this research methodology weblog seems to cover just about anything and everything. To help people sort through…

The Journal of Statistical Software

*Blog post

Year 2006

Statistical computing

The January 2006 issue of Amstat News had the following announcement:

Characterizing reasons for refusal

*Blog post

Year 2006

Exclusions in research

A participant in the IRB Forum raised a question about a research study where people were asked to participate, and when some of them said “no” they were then asked why they…

Handling dropouts in NNT/NNH calculations

*Blog post

Year 2006

Measuring benefit and risk

Someone asked a question on the Evidence-Based Health email discussion group about how to handle dropouts in an NNT/NNH calculation. There is no standard way of handling…

First peek at the cover of my new book

*Blog post

Year 2006

Statistical evidence book

Oxford University Press (OUP) just sent me the first draft of the jacket and cover of the book I am writing, Statistical Evidence in Medical Trials.

Where to go, where to go

*Blog post

Year 2006

Professional details

There are several interesting research conferences this year, and I have to decide quickly which one(s) to attend.

Extreme value distribution

*Blog post

Year 2006

Probability concepts

I got an interesting question about an application in information theory of a statistical distribution called the Type I extreme value distribution. This distribution, also…

An entry in Chance News

*Blog post

Year 2006

Wiki pages

For time to time, I have contributed small items to a web publication called Chance News.

The past year in my weblog

*Blog post

Year 2006

Website details

I just cleaned up the weblog and put all the old entries in separate files in the archive. It was a busy year (though I did slow down a lot in November and December). There…

Vote for me

*Blog post

Year 2005

Being updated

Professional details

I am running for an elected office, the Vice-Chair of District 4, Region 2, of the Council of Chapters for the American Statistical Association. I could make some jokes…

Object oriented features of R

*Blog post

Year 2005

Being updated

R software

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Confidence intervals are needed to evaluate clinical importance

*Blog post

Year 2005

Clinical importance

Back in March, I sent a letter to the American Journal of Psychiatry complaining about their failure to include confidence intervals in their published reports. The journal…

Fractions are funny

*Blog post

Year 2005

Being updated

Measuring benefit and risk

On my web page about odds ratios, I point out the fractions are funny and cite some well known examples of how fractions behave in a counter intuitive fashion. One of the…

Group Sequential Monitoring of Clinical Trials in R

*Blog post

Year 2005

Being updated

Early stopping

R software

It is very expensive to purchase software that performs group sequential monitoring of clinical trials (sometimes called interim analysis). Group sequential monitoring is…

The HapMap project

*Blog post

Year 2005

Being updated

Information theory

One of the research projects I am involved with may make use of the HapMap project (www.hapmap.org). This project is an ambitious effort to document the frequency of most…

Withholding information

*Blog post

Year 2005

Being updated

Blinding in research

A recent query on the IRB Forum asked about a pilot study. The goal of the pilot study was to see if different ways of presenting the materials would lead to an improvement…

Hard learned lessons

*Blog post

Year 2005

Being updated

Data management

It’s been a busy month, as noted below, and in a rush to complete all my projects, I ended up doing some things that may have caused a few problems (nothing permanent, of…

Slow progress on my weblog

*Blog post

Year 2005

Being updated

Website details

You may have noticed how few entries there are in the month of November. That’s just a reflection of the extraordinary surge in work here at Children’s Mercy Hospital.…

Stepwise regression to screen for covariates

*Blog post

Year 2005

Being updated

Covariate adjustment

Someone wrote asking about how best to use stepwise regression in a research problem where there were a lot of potential covariates. A covariate is a variable which may…

Web page for Fisher’s Exact test

*Blog post

Year 2005

Being updated

Statistical computing

I get lots of simple requests like calculate Fisher’s Exact test for this two by two table, and I am happy to help out, but there are free web pages that perform these…

Non-destructive data editing

*Blog post

Year 2005

Being updated

Data management

I recently worked on a project looking at patients having two different types of operations, with and without collar sutures. The data set that the researchers sent to me…

Seventeen years between research and practice

*Blog post

Year 2005

Being updated

Teaching resources

I attended an excellent talk by one of the nurses at CMH on the problems with implementing quality improvement initiatives in health care. She cited an interesting…

A nice definition of anecdotal evidence

*Blog post

Year 2005

Critical appraisal

Robert Todd Carroll, author of The Skeptics Dictionary and creator of the website Skepdic.com, mentioned in a recent newsletter that he has updated his definition for anecdot…

RMA normalization of microarrays

*Blog post

Year 2005

Genomics analysis

If you ask most statisticians if they want raw data or processed data, they will, for the most part, prefer to look at the raw data. There are two reasons for this. First…

Searching for information about the molasses with milk enema

*Blog post

Year 2005

Being updated

Information searching

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A totally negative microarray experiment

*Blog post

Year 2005

Genomics analysis

I’ve been cleaning out my old emails and am finding some real gems of good advice. Someone wrote into the Bioconductor email list wondering what to do when the lowest…

The fate of retracted articles

*Blog post

Year 2005

Being updated

Ethics in research

A member of the Evidence Based Health email discussion group noted an interesting discussion about a recently retracted Cochrane review:

Two nice R libraries

*Blog post

Year 2005

Being updated

R software

I found a couple of nice libraries in R available from CRAN (Comprehensive R Achive Network). The first, vcd, was recommended by a regular contributor to the epidemio-l…

A nonspecific diagnostic test

*Blog post

Year 2005

Being updated

Corroborating evidence

Someone posted a note on the IRBFORUM complaining that the IRB was preventing him/her from volunteering for a test. This company has a very promising “non-intrusive…

Lost page

*Blog post

Year 2005

Being updated

Earlier versions are here and here.

Discovering gene information using OMIM

*Blog post

Year 2005

Genomics analysis

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A simple trick in R

*Blog post

Year 2005

Being updated

R software

There may be times when you have a string in R that represents a specific R command. How would you run this command. This was answered recently on the Bioconductor mailing…

Responding to a critique of meta-analysis

*Blog post

Year 2005

Being updated

Systematic overviews

A contributor to the Evidence-Based Medicine list offered a possible criticism of meta-analysis. The criticism was along the lines of (I am paraphrasing and summarizing):

Quality control exercises, Part 2

*Blog post

Year 2005

Quality control

I tried a pilot experiment of a quality control exercise. It seemed to go fairly well. The goal of the exercise was to flip a coin from a table onto a target on the floor…

Sample size for a binomial confidence interval

*Blog post

Year 2005

Being updated

Sample size justification

Someone asked me for some help with a homework question. I hesitate to offer too much advice in these situations because I don’t want to disrupt the teacher’s efforts to get…

HIPAA and research

*Blog post

Year 2005

Being updated

Privacy in research

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

An error slips through the peer review process

*Blog post

Year 2005

Being updated

Diagnostic testing

A group of residents wanted me to look at an article because they were confused about the calculation of the likelihood ratio. The numbers that they got were quite different…

All models are

*Quotation

Year 2005

Statistical models

All models are wrong, but some are useful George Box, as quoted in wikiquote.

Dishonesty in medical research

*Blog post

Year 2005

Being updated

Ethics in research

Roy Poses, a regular contributor to the email discussion group Evidence Based Health wrote a provocative email pointing out the manipulation of research, ghost-writing, and…

Free statistics software

*Blog post

Year 2005

Being updated

Statistical computing

The number and quality of free statistical software offerings appears to be increasing. Here are two interesting sites that offer good quality software for free.

Testing for bimodality

*Blog post

Year 2005

R software

Stata software

Testing for bimodality is a rather tricky thing. A recent discussion of tests of bimodality on edstat-l, though, yielded a few promising leads relating to the Dip test.

Self experimentation

*Blog post

Year 2005

Being updated

Ethics in research

Stephen Dubner and Steven D. Levitt, authors of the hot selling book, Freakonomics: A Rogue Economist Explores the Hidden Side of Everything, have a regular column in the…

Science mentoring

*Blog post

Year 2005

Being updated

Teaching resources

I received an email notice through the Kansas/Western Missouri chapter of the American Statistical Association about “Meet the Science Mentor Day.” This is a half day…

Two articles debating equipoise

*Blog post

Year 2005

Being updated

Equipoise in research

A frequent contributor to the IRBForum (HM) mentioned a couple of articles that discuss equipoise and which are well worth discussing in detail.

From my associations with doctors in controlled trials

*Quotation

Year 2005

Research ethics

...from my associations with doctors in controlled trials I have learned that the better the statistician understands the doctor/patient relationship and the doctor’s very…

Quality control exercises

*Blog post

Year 2005

Being updated

Quality control

I’ve taught several courses on Quality Control, and the best part is the practice exercises.

What’s New in SPSS version 14.0

*Blog post

Year 2005

Being updated

SPSS software

I attended a web seminar, What’s New in SPSS version 14.0, taught by Meta Brown, a Senior Systems Engineer with SPSS, Inc. Version 14 will ship in October 2005. The major…

Another disaster averted

*Blog post

Year 2005

Being updated

Data management

When you are importing a file from one system to another, lots of little things can trip you up. Here’s an example, and it shows a very subtle problem.

Contacting and working with me

*Blog post

Year 2005

Being updated

Professional details

This page is outdated, but I am keeping it because I am an electronic pack rat.

Sample size for a binary endpoint

*Blog post

Year 2005

Being updated

Sample size justification

Someone sent me an email asking for the sample size needed to detect a 10% shift in the probability of recurrence of an event after one of two different surgical procedures…

IRBs and scientific validity

*Blog post

Year 2005

Being updated

Ethics in research

One of the regular posters on the edstat-l mailing list shared a comment that is commonly held among many of the people I have talked to.

Case cohort design

*Blog post

Year 2005

Observational studies

During a consultation about an NIH research grant, the term “case cohort design” came up. The Case Cohort design is similar to a nest Case Control design, but also has some…

Dates in Excel and R

*Blog post

Year 2005

Being updated

R software

Every program uses a slightly different method for calculating date values. Excel, for example, counts the number of days since the start of 1900 (January 1, 1900=1) for…

All scientific work…

*Quotation

Year 2005

Critical appraisal

Being updated

All scientific work is incomplete—whether it be observational or experimental. All scientific work is liable to be upset or modified by advancing knowledge. That does not…

Reporting of adverse events

*Blog post

Year 2005

Adverse events

Being updated

Most Institutional Review Boards (IRBs) have difficulty coping with the volume of adverse events that study sponsors report to them. The FDA held a public meeting about this…

Converting an odds ratio to a relative risk

*Blog post

Year 2005

Being updated

Measuring benefit and risk

The odds ratio and the relative risk do not always agree, especially when the baseline risk level in the control group is large. I have a simple Excel spreadsheet that will…

Effective communication about randomized clinical trials (created 2005-02-22)

*Blog post

Year 2005

Being updated

Allegations of scientific misconduct (August 1, 2005)

*Blog post

Year 2005

Being updated

An inefficient approach to randomization (August 10, 2005)

*Blog post

Year 2005

Being updated

More on the weaknesses of randomized trials (created 2005-02-14)

*Blog post

Year 2005

Being updated

S-PLUS Clinical Safety Miner (March 10, 2005, Model, Software)

*Blog post

Year 2005

Being updated

A third search for the evidence

*Blog post

Year 2005

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Publication in the ChanceWiki

*Blog post

Year 2005

Wiki pages

Chance News has changed recently to a Wiki format.

Information content of a continuous distribution

*Blog post

Year 2005

Being updated

Information searching

I was browsing through the book

Overview of evidence-based-medicine

*Blog post

Year 2005

Being updated

Teaching resources

The Archives of Disease in Childhood has a series of articles on evidence-based Medicine.

Expected value and moments

*Blog post

Year 2005

Being updated

Probability concepts

Someone asked me what a statistical moment is. That’s a rather technical term and is not needed except in rather theoretical and mathematical discussions. But it is still…

Moving R objects

*Blog post

Year 2005

Being updated

Data management

R software

I regularly work from home on my laptop, and when I need to re-run some analyses in R, I usually just re-create the original data sets. But there are several ways you can…

Merging in R

*Blog post

Year 2005

Being updated

R software

Rmarkdown code

Merging is tricky in any program, and you have to be sure that you know what you are doing. I have found that keeping an index variable will allow me to backtrack and find…

Registration of clinical trials

*Blog post

Year 2005

Being updated

Publication bias

International Committee of Medical Journal Editors (ICMJE) has called for a requirement for registration of clinical trials. All clinical trials that start recruiting on or…

More on regular expressions

*Blog post

Year 2005

Being updated

Data management

As I work more and more with microarrays, the more I realize that having a knowledge of regular expressions will help. For example, I had a comma separated file (.CSV) and…

Counterpoint on Google Scholar

*Blog post

Year 2005

Being updated

Information searching

A recently published article:

Very low values from Cronbach’s Alpha

*Blog post

Year 2005

Measuring agreement

Someone came to me with an analysis of a scale of 16 items, where the Cronbach’s alpha computed for that scale was only 0.14. The first thing you should look for in this…

The difference between absolute risks and relative risks

*Blog post

Year 2005

Measuring benefit and risk

There are two general ways to compare a treatment and a control group, relative comparisons and absolute comparisons. For a relative comparison, the basic computation is…

Confidence interval for a correlation coefficient

*Blog post

Year 2005

Confidence intervals

Sample size justification

In many exploratory research studies, the goal is to examine associations among multiple demographic variables and some outcome variables. How can you justify the sample…

What does a 60% drop mean?

*Blog post

Year 2005

Being updated

Measuring benefit and risk

A friend sent me an email quoting the following statistic: “A woman’s chances of getting married dropped 60% for every rise of 15 points in her IQ, according to an English…

Step-down procedures for multiple comparisons

*Blog post

Year 2005

Being updated

Hypothesis testing

In some research studies, you have a large and difficult to manage set of outcome measures. This is especially true in microarray experiments, where for thousands or tens of…

Some articles on meta-analysis

*Blog post

Year 2005

Being updated

Systematic overviews

I found a couple of interesting articles on meta-analysis that are difficult to classify:

More on the retroactive prayer study

*Blog post

Year 2005

Being updated

Corroborating evidence

I discuss an interesting study on the effects of prayer (Leibovici 2001) published in BMJ, where the researcher prayed over a set of charts that represented outcomes…

I abhor Lilliefor and other tests of normality

*Blog post

Year 2005

Statistical assumptions

Someone asked me about a log transformation for their data. It seemed like a good idea, based on my general comments on the log transformation, but the test of significance…

Another top ten study in EBM (February 14, 2005)

*Blog post

Year 2005

Being updated

Ten research studies that anyone teaching EBM should be familiar with (January 17, 2005)

*Blog post

Year 2005

Being updated

Another search for evidence

*Blog post

Year 2005

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

When the F test is significant, but Tukey is not (created 2005-09-09)

*Blog post

Year 2005

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

When can I stop my CQI study?

*Blog post

Year 2005

Being updated

Early stopping

I was asked today about a CQI project where children were being tested for a certain condition, but they never tested positive. This was going on for over a year and there…

Taking charges of conflicting interest too far

*Blog post

Year 2005

Broken link

Conflict of interest

You should always be aware of potential conflicts of interest. Sometimes researchers allow a financial incentive to influence their research and end up skewing the data to…

The paired availability design

*Blog post

Year 2005

Being updated

Observational studies

In the quest to finish my book on Statistical Evidence, I had to leave some material on the cutting room floor. One of the nicer descriptions was about the paired…

Changes to STAT-L/sci.stat.consult

*Blog post

Year 2005

Broken link

Obsolete page

Teaching resources

Note: STAT-L is no longer active. I am keeping this page around for historical reasons.

Importing value labels from Access into SPSS

*Blog post

Year 2005

Being updated

Data management

Someone asked about importing data from Access into SPSS. The Access file has value labels (e.g., 1=Male, 2=Female, 3=Missing) and wanted to know if there was any<U+FFFD>…

When one group only has a single observation

*Blog post

Year 2005

Being updated

Small sample size issues

Someone asked me about a lab study comparing expression levels for two groups of patients. The first group has two copies of a gene and the second group has three copies of…

Another open site closes

*Blog post

Year 2005

Being updated

Writing research papers

I often link to interesting resources on the web, and it is always distressing to find that content which had been available freely is now available only through…

Adjusting for covariate imbalance

*Blog post

Year 2005

Being updated

Covariate adjustment

Here’s a graph I want to insert in my book. It illustrates how to adjust for covariate imbalance. The data comes from the Data and Story Library

Computing normal probabilities

*Blog post

Year 2005

Being updated

Statistical computing

One of the programs here at Children’s Mercy Hospital is helping me take an Excel spreadsheet and developing a Windows program that will do the same calculations faster and…

What is critical thinking?

*Blog post

Year 2005

Being updated

Critical appraisal

A lot of people use the term “critical thinking” in an offhand way. Usually the writer who uses this term is trying to imply that anyone who disagrees with the writer’s…

More on searching the literature

*Blog post

Year 2005

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Geometric distribution

*Blog post

Year 2005

Being updated

Probability concepts

Someone asked me about a game where A, B, and C toss a coin in order (A first, then B, then C, then A again, etc.) until someone gets a heads on their coin flip. What are…

You have to make a distinction between the science and the technological applications

*Quotation

Year 2005

Theory versus practice

Earlier versions are here and here.

Hedge’s G

*Blog post

Year 2005

Being updated

Systematic overviews

Someone asked me today about Hedge’s G. I had never heard of it before, but if you do a web search, you will find

Post hoc power is never justified

*Blog post

Year 2005

Being updated

Post hoc power

Someone wrote in and was upset that a referee was insisting on post hoc power for all the outcome measures, and he only wanted to compute post hoc power for the negative…

Confidence intervals around a safety level

*Blog post

Year 2005

Being updated

Confidence intervals

Someone asked me about an environmental clean up. The government told them that the location was cleaned up to a 90% confidence level of the standard. Would this give the…

String manipulations in R

*Blog post

Year 2005

Being updated

Data management

R software

As part of my efforts to analyze microarray data, I am finding that I need to do simple string manipulations in R. Here is a list of functions that might help.

Preserving spacing in html code

*Blog post

Year 2005

Being updated

Website details

Note that this page is obsolete (I am writing this note on 2020-10-26). I am currently transitioning to using Markdown and RMarkdown for my website.

Searching the literature

*Blog post

Year 2005

Being updated

Information searching

Next week, our hospital will have a seminar on Reiki. I thought it would be useful to see what evidence there was on this technique. My search included access to several…

Meta-analysis talk

*Blog post

Year 2005

Being updated

Systematic overviews

Today I gave a talk on meta-analysis. I started with a general overview of meta-analysis, and then discussed some of the particular problems associated with a meta-analysis…

PubMed tags

*Blog post

Year 2005

Being updated

Information searching

Searching in PubMed can be tricky. If you don’t find what you want the first time, it may help to specify exactly what part of the PubMed record you want to search for.

Determining the optimal threshold for a diagnostic test

*Blog post

Year 2005

Being updated

Diagnostic testing

Someone asked me about how to design an experiment that would use the ROC curve to determine an appropriate threshold for a diagnostic test.

Searching the Internet

*Blog post

Year 2005

Being updated

Information searching

A response to a question on the stat-l discussion group provided a clever way of searching the Internet. Someone asked about finding references about how to analyze ordinal…

MedStats discussion group

*Blog post

Year 2005

Being updated

Teaching resources

If you don’t get enough email already, a new discussion group, MedStats, was created recently. MedStats is hosted on Google Groups. The main page for MedStats is groups.googl…

More than 90% censored values

*Blog post

Year 2005

Survival analysis

Someone asked me about running a Cox proportional hazards regression model when over 90% of the observations were censored. That means (if the outcome of interest was…

The test of a first rate intelligence

*Quotation

Year 2005

Human side of statistics

The test of a first rate intelligence is the ability to hold two opposed ideas in the mind at the same time and still retain the ability to function. F Scott Fitzgerald…

Measuring agreement

*Blog post

Year 2005

Being updated

Measuring agreement

Someone reviewing a paper asked me about all the “weird statistics” being used in the paper, such as the Bland-Altman plot and Deming regression.

Incidence density ratio

*Blog post

Year 2005

Being updated

Measuring benefit and risk

Someone asked me about a technical term, incidence density ratio, that was used in an article:

S-plus version 7

*Blog post

Year 2005

Being updated

Statistical computing

I attended a web seminar by David Smith introducing the latest version of S-plus, version 7.This software, produced by Insightful Corporation, is one of my favorite products…

Profile analysis and MANOVA

*Blog post

Year 2005

Being updated

Multilevel models

Someone asked me about profile analysis as alternative analysis to MANOVA (Multivariate Analysis of Variance). Typically you would use profile analysis when the outcome…

Fair Use of copyrighted material

*Blog post

Year 2005

Being updated

Website details

I get many requests to link to my web pages, and I always grant these requests. Other people ask if they can use portions of my material on their web pages or in their…

Presenting Numbers, Tables, and Charts

*Blog post

Year 2005

Being updated

Descriptive statistics

I got a nice email from Sally Bigwood, one of the coauthors of

Tolerance limits

*Blog post

Year 2005

Being updated

Quality control

Someone asked me about the difference between control limits and tolerance limits.

Do I have enough data after 24 months of time?

*Blog post

Year 2005

Being updated

Clinical importance

Early stopping

Someone asked me about a correlation coefficient that he computed on a data set that represented 24 months of data collection. A particular correlation of interest (a…

Summing ordinal data

*Blog post

Year 2005

Being updated

Descriptive statistics

You have a questionnaire which asks several related questions on a Likert scale (1=Strongly Disagree, 2=Disagree, etc.). You want to add these items together and then report…

Where is the confidence interval?

*Blog post

Year 2005

Being updated

Clinical importance

Confidence intervals

A recent letter to the editor,

Non-random samples

*Blog post

Year 2005

Being updated

Observational studies

Someone sent me an email asking about a project that involved interviews of women at higher levels of management in an organization. This is a rather small group, and might…

Open-ended questions on a survey

*Blog post

Year 2005

Survey design

No one seems to talk about how to handle those pesky open-ended questions you see on a survey. I usually hold my breath and hope that the researcher doesn’t think to mention…

Inferential and descriptive statistics

*Blog post

Year 2005

Being updated

Descriptive statistics

Someone asked me whether it was okay to define a correlation coefficient as a descriptive statistic. It depends on whether the correlation is being used to describe a…

More on information theory models

*Blog post

Year 2005

Being updated

Information theory

Some of the people I work with have used information theory extensively in their work. A good summary of their efforts appears in

Surrogate outcomes

*Blog post

Year 2005

Being updated

I’m on the mailing list of the Alliance for Human Research Protection, and they highlighted a book review:

A collection of randomized and non-randomized studies

*Blog post

Year 2005

Being updated

Observational studies

Randomization

I’m updating some of my training classes to use examples from open source journals, because it is easier for me to include content of these articles directly in the web pages.

Coming soon!

*Blog post

Year 2005

Being updated

Website details

Under the details section of these web pages, I have a page talking about future plans. After months of neglect, I took the time to update that page. I also need to keep…

Meta-analysis for a diagnostic test

*Blog post

Year 2005

Being updated

Systematic overviews

What I originally wrote for this page has been replaced by

Language resources

*Blog post

Year 2005

Being updated

Information searching

Once in a while, I will get an email or find a website written in a foreign language. The best way to handle this is through BabelFish:

Using Mathematica and Matlab for Statistics

*Blog post

Year 2005

Being updated

Statistical computing

Mathematica, produced by Wolfram Research, is a program which performs numeric and symbolic computations. It also can produced sophisticated graphical images. There are two…

Stratified Cox regression models

*Blog post

Year 2005

Being updated

Survival analysis

Someone sent me an email asking about a Cox regression model that included a strata for clinics. What’s the best way to handle strata? That’s a tricky question to answer.…

Meta-analysis

*Blog post

Year 2005

Being updated

Systematic overviews

Meta-analysis is the quantitative combination of results from multiple research studies. There are three steps in a typical meta-analysis model.

Digitizing a graph

*Blog post

Year 2005

Being updated

Data management

Someone brought me a graph with a trend line relating body surface area (BSA) to various cardiac measurements. This graph showed both the trend line and limits at +/-2…

Quality of published research

*Blog post

Year 2005

Being updated

Systematic overviews

One of the big advantages of meta-analysis is that it allows you to review a series of publications in an area to see if there are any gaps or quality shortfalls. While I…

Publicon software

*Blog post

Year 2005

Being updated

Statistical computing

Wolfram Research, makers of the famous software for symbolic mathematical calculations, Mathematica, have released a new product for technical publications, Publicon.…

Selective reporting of research findings

*Blog post

Year 2005

Being updated

Publication bias

I have talked extensively about publication bias in my weblog

Clinical importance

*Blog post

Year 2005

Being updated

Clinical importance

Many journal authors have the bad habit of looking just at the p-value of a study and ignoring the clinical importance of their findings. If they get a small p-value, which…

Cumulative meta-analysis

*Blog post

Year 2005

Being updated

Systematic overviews

This figure below, published in

Analysis of subgroup results

*Quotation

Year 2005

Multiple comparisons

Analysis of subgroup results in a clinical trial is surprisingly unreliable, even in a large trial. This is the result of a combination of reduced statistical power…

Lost page

*Blog post

Year 2005

Being updated

Earlier versions are here and here.

It seems to me reasonable to look for benefit or harm

*Quotation

Year 2005

Subgroup analysis

It seems to me reasonable to look for evidence of benefit or harm in certain biologically plausible subgroups, even though the statistical basis for this evidence is not…

Technology to end spam

*Blog post

Year 2005

Being updated

Bayesian statistics

In my job I get a lot of spam, partly because I listed my email address on my web site until just recently. The research community is trying to find technological solutions…

Sample size calculation for a nonparametric test

*Blog post

Year 2005

Being updated

Sample size justification

I got an email inquiry about how to calculate power for a Wilcoxon signed ranks test. I don’t have a perfect reference for this, but I do have a brief discussion on sample…

PowerPoint Counterpoint

*Blog post

Year 2005

Being updated

Presenting research

I am a rather harsh critic of PowerPoint,

The costs of a false positive test

*Blog post

Year 2005

Being updated

Diagnostic testing

The New York Times had an excellent article on newborn screening tests.

Growth curves

*Blog post

Year 2005

Being updated

Nonlinear regression

The New York Times has a nice article about Dr. James Tanner, an expert on childhood growth.

Adjusting for a baseline measurement

*Blog post

Year 2005

Broken link

Covariate adjustment

Someone asked me today about how to analyze a two group experiment with a baseline value. This is common research design. Researchers will assess all patients at the…

More on the top ten studies in EBM

*Blog post

Year 2005

Being updated

Teaching resources

I may never get this paper done, but the effort is still worthwhile in that I am learning a lot. I rediscovered a wonderful web page developed by Ben Djulbegovic, Randomized…

Taguchi methods

*Blog post

Year 2005

Being updated

Quality control

Genichi Taguchi was a Japanese engineer and statistician who developed a wide range of statistical tools for improving the quality of industrial manufacturing. These tools…

Sackettisation, the artificial linkage

*Quotation

Year 2005

Evidence Based Medicine

Sackettisation ... the artificial linkage of a publication to the evidence-based medicine movement in order to improve sales. bmj.bmjjournals.com/cgi/content/full/320/7244/12…

Scientific papers serve the needs of their authors

*Quotation

Year 2005

Writing research papers

...scientific papers serve the needs of their authors above those of their readers. Why else would a journal devote five pages to a paper that reached this conclusion? “In…

Security tends to be

*Quotation

Year 2005

Being updated

Incomplete page

Privacy in research

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Developing good practice guidelines

*Blog post

Year 2005

Being updated

Teaching resources

A physician here, Lloyd Olson, who has been aggressively promoting Evidence Based Medicine suggested the following interesting article on practice guidelines.

Report cards

*Blog post

Year 2005

Being updated

Evidence Based Medicine

Teaching resources

The Minnesota Department of Health recently published a report over a 15 month period that documenting 99 events occurring in Minnesota hospitals that should never occur.…

Side effects of Cox-2 inhibitors

*Blog post

Year 2005

Being updated

Measuring benefit and risk

There has been so much published about side effects of Cox-2 inhibitors that it is hard to keep up with the evolving story. Here are a few recently released articles:

Moderator variables

*Blog post

Year 2005

Being updated

Covariate adjustment

I’ve always disliked the excessive use of detailed terminology, but when someone asked me about moderator variables, I had to look up the details. Basically, a moderator…

Public access to publications from NIH-funded research

*Blog post

Year 2005

Being updated

Writing research papers

The NIH is now requesting publication in PubMed Central of research publications that is supported in whole or in part by NIH grants. The authors can designate a time delay…

Optimization using the MM algorithm

*Blog post

Year 2005

Being updated

Statistical computing

A comment on EDSTAT-L reminded me about this important issue. Many problems in Statistics involve finding an optimal point of a rather complex and messy function. In some…

Relationship between sample size and p-values

*Blog post

Year 2005

Being updated

Pvalues

I got a rather basic inquiry about p-values, but it is worth mentioning. Someone had a data set with 9,000 observations and was unhappy with the p-value that he got in a…

Control charts for monitoring mortality rates

*Blog post

Year 2005

Being updated

Adverse events

One of the trickiest problems in Medicine is trying to identify whether an unusual trend in mortality rates is an indication of an incompetent physician, or worse, a…

Continuous variables in a logistic regression model

*Blog post

Year 2005

Being updated

Logistic regression

I got a question by email that asked, in a rather indirect way, how to interpret the odds ratio estimate for a continuous variable in a logistic regression model. It turns…

A small p-value does not mean a large difference

*Blog post

Year 2005

Being updated

Pvalues

Someone asked me if the p-value for a t-test indicates the size of the difference between two groups. It turns out that the p-value is related both to the size of the…

Sampling the entire population

*Blog post

Year 2005

Being updated

Descriptive statistics

A commonly occurring question is what to do when you have a small population that you are sampling and your sample effectively constitutes all or almost all of the…

A surprising application of the harmonic mean

*Blog post

Year 2005

Being updated

Statistical theory

The radio show, Car Talk, has a puzzle that they read every week on the show. Usually, it is some unusual or unexpected problems with automobiles, but Ray and Tom Magliozzi…

Statistical Evidence in Medical Trials

*Blog post

Year 2008

Being updated

Statistical evidence book

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Placing consecutive dates in a column of an SPSS file

*Blog post

Year 2005

SPSS software

Someone gave me a data set with 549 rows of data. The first row corresponded to observations on 06/01/2003, the second to 06/02/2003, and so forth through 11/30/2004. She…

Re-weighting the data

*Blog post

Year 2005

Being updated

Covariate adjustment

A recent article

A mathematician is

*Quotation

Year 2005

Mathematics

A mathematician is a machine for turning coffee into theorems. Paul Erdos. It’s worth noting that Paul Erdos is one of the most eccentric mathematicians, a group that…

Steps in a typical Bayesian model

*Blog post

Year 2005

Bayesian statistics

I . “Should proponents of EBM be concerned about understanding the Bayesian philosophy? In my opinion, no. I think we’ll gradually see Bayesian philosophy creep in to the…

No human investigation can be called real science

*Quotation

Year 2005

Mathematics

No human investigation can be called real science if it cannot be demonstrated mathematically. Leonardo da Vinci

Steps in a typical Bayesian model

*Blog post

Year 1999

Being updated

Bayesian statistics

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Twas the night before surgery

*Quotation

Year 2005

Ethics in research

A Visit to the ER from St. Nick

What do you call the removal of

*Quotation

Year 2005

Privacy in research

Q. What do you call the the removal of individually identifiable health information from health records? A. HIPAAectomy. Found at www.hipaadvisory.com/live/FAQ/humor.htm. No…

How good is your intuition?

*Blog post

Year 2005

Being updated

Critical appraisal

One definition of Evidence Based Medicine is

Summary Receiver Operating Characteristic Curve

*Blog post

Year 2005

Being updated

Systematic overviews

In the past week, I have had two inquiries about how to perform a meta-analysis of studies of a diagnostic test. An intriguing idea that I discovered in researching this is…

Adjusted odds ratios

*Blog post

Year 2005

Covariate adjustment

Someone asked me today how to compute an adjusted odds ratio. He has a case control study where cases represent cancer patients. He also has various Single Nucleotide…

Testing baseline imbalance in a randomized study

*Blog post

Year 2005

Covariate adjustment

Randomization will roughly balance out the covariates between the treatment group and the control group because of the law of large numbers. Once in a while, though, an…

The Digital Object Identifier

*Blog post

Year 2005

Being updated

Information searching

Many journals are now using the Digital Object Identifier (DOI) to reference their publications.

Confusion about p-values

*Blog post

Year 2005

Hypothesis testing

Someone wrote to me with a statement that represents a commonly held, but false belief. He stated, in effect, that a p-value of 0.06 means that there is only a 6%…

More thoughts on equipoise

*Blog post

Year 2005

Being updated

Equipoise in research

Vital to the ethical conduct of a clinical trial is the concept of equipoise, that a researcher is clinically indifferent or genuinely uncertain, as to whether a new therapy…

Small relative risks

*Blog post

Year 2005

Being updated

Measuring benefit and risk

I found a quote on the Skeptic’s Dictionary web site that is worth commenting on. The author, Robert Todd Carroll was describing the Vioxx controversy and the lawyers who…

Forest plots

*Blog post

Year 2005

Being updated

Systematic overviews

Many meta-analyses use a graph known as a forest plot. I was always confused by the funny squares in a forest plot, so I looked for a description. An example of a forest…

Two cautionary tales about data mining

*Blog post

Year 2005

Data mining

I attended a 7am seminar this morning on data warehousing and data mining, which was quite good. It reminded me of a couple of stories I heard about the pitfalls of data…

Odds ratios less than one

*Blog post

Year 2005

Being updated

Measuring benefit and risk

Someone sent me an email asking how to interpret an odds ratio less than 1. An odds ratio of 1 means that the odds of an event is the same in both the treatment and control…

Spectrum Bias

*Blog post

Year 2005

Being updated

Diagnostic testing

Observational studies

I tried to start a page on diagnostic tests a while back, but have not had the time to fully develop it. One of the important issues for diagnostic tests is spectrum bias.

Monetary incentives

*Blog post

Year 2005

Being updated

Ethics in research

Someone on the IRBForum asked about monetary incentives in research. This is a controversial area (see the OHRP website, Foy 1998, Sugarman 2004, Young 2001), and especially…

Best EBM methods or teaching papers in 2004

*Blog post

Year 2005

Evidence Based Medicine

Paul Glasziou compiled a list for the best EBM papers in 2004. These papers had to deal with either methods for EBM or teaching of EBM. Here is the list:

More on conflicts of interest

*Blog post

Year 2005

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Examples of confidence intervals

*Blog post

Year 2005

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

What alternative medicine can teach us about evidence-based medicine

*Blog post

Year 2005

Being updated

Ethical principles for Complementary and Alternative Medicine

*Blog post

Year 2005

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

The ethics of randomization

*Blog post

Year 2005

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

A controversial meta-analysis

*Blog post

Year 2005

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Media interview tips

*Blog post

Year 2005

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Statistical Analysis of Microarrays by Insightful Software

*Blog post

Year 2005

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

The S+ CorrelatedData Library (May 19, 2005)

*Blog post

Year 2005

Being updated

Multilevel models

Obsolete page

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Standard deviation versus standard error (May 16, 2005)

*Blog post

Year 2005

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Two articles in the Chance Wiki

*Blog post

Year 2005

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Testing for side effects

*Blog post

Year 2004

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Weblinks for December 2004

*Blog post

Year 2004

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Zhenya

*Blog post

Year 2004

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Designing a questionnaire

*Blog post

Year 2004

Survey design

I’m behind in my reading of the British Medical Journal, and the first issue I looked at today has a gem of an article.

Is the randomized trial the gold standard for research?

*Blog post

Year 2004

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Can you recommend a good book?

*Blog post

Year 2004

Teaching resources

Being updated

Outcomes research

*Blog post

Year 2004

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Design and analysis of pilot studies

*Blog post

Year 2004

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Zhenya

*Blog post

Year 2004

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Simpson’s Paradox

*Blog post

Year 2004

Statistical theory

Someone wrote to the Evidence Based Health email discussion group about a theoretical situation where someone had an estimated risk of disease based on a study that showed…

Subgroup analysis

*Blog post

Year 2004

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Hiring a statistician after the data has been collected

*Quotation

Year 2004

Human side of statistics

“Hiring a statistician after the data has been collected is like hiring a physician when your patient is in the morgue. He might be able to tell you what went wrong, but he…

Neyman bias

*Blog post

Year 2004

Measuring benefit and risk

Selection of controls in a case-control study is difficult enough, but you also have to worry about the selection of the cases. Do you select incident cases (for example all…

Prayer studies

*Blog post

Year 2004

Corroborating evidence

I’ve been meaning to write a web page about the series of studies that seem to indicate that groups of patients receiving prayer get better health outcomes than the control…

New in SPSS version 13.0

*Blog post

Year 2004

SPSS software

I attended a web seminar on the new enhancements in version 13.0 of SPSS software. The most notable change is in date calculations.

Entrenched beliefs

*Blog post

Year 2004

Critical appraisal

A member of the Evidence Based Health listserv wrote about a workshop he taught on Evidence Based Medicine (EBM). It went pretty well, he thought until he overheard a…

Confidence intervals

*Blog post

Year 2003

Being updated

Can you give me a simple explanation of what a confidence interval is?

Measuring heterogeneity in meta-analysis

*Blog post

Year 2004

Systematic overviews

While browsing through the archives of the British Medical Journal, I noticed an excellent article on measuring heterogeneity in meta-analysis. There is a new measure…

Lost page

*Blog post

Year 2004

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Controversy over stopping a study early

*Blog post

Year 2004

Early stopping

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Alternatives to equipoise

*Blog post

Year 2004

Equipoise in research

Stephen Senn wrote an interesting article a couple of years ago that provides an intriguing alternative to the concept of equipoise. I wrote about equipoise in a web page…

Intellectual conflict of interest

*Recommendation

Year 2004

Conflict of interest

Jeanne Lenzer. FDA bars own expert from evaluating risks of painkillers. BMJ 2004-11-18; 329: 1203. doi:10.1136/bmj.329.7476.1203. This article is behind a paywall.

Unequal sample sizes

*Blog post

Year 2004

Sample size justification

For some reasons, it seems to unnerve people when the sample size in the treatment and control group are not the same. They worry about whether the tests that they would run…

Software patents

*Blog post

Year 2004

Statistical computing

I have always found the concept of software patents confusing. I am listed as a co-inventor on a software patent, so perhaps that raises a conflict of interest. Still, here…

Ratio of observations to independent variables

*Blog post

Year 2004

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Discrepancy between univariate and multivariate models

*Blog post

Year 2004

Modeling issues

Someone asked me about an analysis that showed certain factors were predictive of a health outcome when considered individually. When these factors were included in a…

Testing multinomial proportions

*Blog post

Year 2004

Probability concepts

I received an email inquiry about a problem that seems simple enough, but which just doesn’t seem to have an easy answer. This person gave the following hypothetical data.

Confidence intervals for complex research designs

*Blog post

Year 2004

Sample size justification

Someone asked me by email about confidence intervals in complex research designs. This person had rejected the use of post hoc power calculations, and wanted instead to use…

Research on therapies that have no known mechanism of action

*Blog post

Year 2004

Corroborating evidence

Several people on the IRBForum have made comments along the lines that research on certain alternative medicines (such as homeopathy) has no scientific merit because there…

Anecdotal information

*Blog post

Year 2004

Critical appraisal

Anecdotal information is problematic for several reasons, and I have highlighted some of these reasons in a speech I gave at the 2004 meeting of the Midwest Society for…

Unblinding at the end of a study

*Blog post

Year 2004

Blinding in research

When a study a placebo controlled study is completed, patients in both arms of the study are often offered the active drug at the end of the study at no cost as a way of…

Automating statistical analyses

*Blog post

Year 2004

Statistical computing

Many of my projects involve writing a program in my text editor (Textpad), copying it into the clipboard, and then pasting it into a statistical program like S-plus or Stata.…

Unnecessary diagnostic tests

*Blog post

Year 2004

Diagnostic testing

You would think that you can never have enough information about your health. Barring financial considerations, the more testing the better.

Top six mistakes in teaching EBM

*Blog post

Year 2004

Teaching resources

I attended a lunch roundtable session on the role of statisticians in teaching Evidence-Based practice to future clinicians. I didn’t get a chance to write up a summary of…

The price of Kaplan-Meier

*Blog post

Year 2004

Survival analysis

I rarely find time to read the Statistics journals anymore, but I did run across an excellent article in the September 2004 issue of JASA.

Multiple degree of freedom tests

*Blog post

Year 2004

Analysis of variance

Someone sent me an email describing a situation where an interaction effect in SPSS had a large p-value, but one of the individual components of that interaction had a small…

Sample size for an ordinal outcome

*Blog post

Year 2004

Sample size justification

Someone asked me for some help with calculating an appropriate sample size for a study comparing two treatments, where the outcome measure is ordinal (degree of skin…

A simple microarray experiment

*Blog post

Year 2004

Data mining

Someone just gave me some data with a small microarray. There are four exposed animals (Exp.1 through Exp.4) and four control animals (Exp.5 through Exp.8). The microarray…

What’s the best statistical model?

*Blog post

Year 2004

Modeling issues

Someone asked me by email about the advantages and disadvantages of various statistical models (multinomial logistic regression, ordinal logistic regression, and structural…

Rates versus proportions

*Blog post

Year 2004

Confidence intervals

Many people use the words “rates” and “proportions” interchangeably, but there is an important distinction that I draw.

Printer friendly versions of web pages

*Blog post

Year 2004

Website details

I use Microsoft FrontPage, and their newsletter listed a resources for creating printer friendly web pages. I dislike the idea of having a separate set of pages for…

International Classification of Functioning, Disability, and Health

*Blog post

Year 2004

Teaching resources

Donald Lollar presented a seminar: “The International Classification of Functioning, Disability, and Health (ICF).” The ICF is a framework for classifying health status that…

Full-Body Computed Tomography Screening

*Blog post

Year 2004

Diagnostic testing

Full body scans represent a good example of the conflicting considerations when you need to evaluate a screening test. A full body scan uses a CT (Computerized Tomography)…

Nitty Gritty NIH

*Blog post

Year 2004

Grant writing

Bill Caskey talked about some of the nitty gritty details of the NIH Grant process. His talk focused mostly on what happens after a grant gets funded.

More on information theory models

*Blog post

Year 2004

Information theory

I received a few suggestions for interesting web sites today. They deal with information theory and trying to establish causation.

Report cards

*Blog post

Year 2004

Unusual data

I’m working on a project looking at some outcomes that might eventually become part of a report card or benchmarking system. This is an area fraught with controversy and it…

Statistical software

*Blog post

Year 2004

Statistical computing

Back when I was writing the FAQ (Frequently Asked Questions) for stat-l/sci.stat.consult, I had a question about how to contact commercial statistical software vendors and wh…

Free Full Text on the Web

*Blog post

Year 2004

Writing research papers

As I mention at the top of the weblog, I preferentially try to cite medical literature where there is free full text available on the web. There are several journals who…

Selection bias

*Blog post

Year 2004

Exclusions in research

The CarTalk radio show has an interesting puzzle every week and often these puzzles involve mathematics. These puzzles can sometimes help you understand complex mathematical…

Stratified randomization

*Blog post

Year 2004

Randomization

A writer on the IRB Discussion Forum asked a question about how to explain stratified randomization in an informed consent document.

Unbalanced sample sizes for evaluating a diagnostic test

*Blog post

Year 2004

Diagnostic testing

I get a lot of questions about unbalanced sample sizes. Quite often the mechanics of the research protocol make it easier to find a lot of patients in one group and only a…

Microsoft Excel Pivot Tables

*Blog post

Year 2004

Statistical computing

Someone at my church wanted some advice about exploring relationships in a survey that he had taken. He asked a bunch of demographic questions (age, sex, income, etc.) and…

Searching for bimodality

*Blog post

Year 2004

Statistical theory

One of the people I work with is always looking for hidden subgroups in his data. For him, this is a starting point for exploring for genetic variations.

So you want to volunteer for a research study?

*Blog post

Year 2004

Exclusions in research

Here’s a draft of a speech that I am planning to give on August 5, 2004 for the Bluejacket Toastmasters humorous speech competition.

Secondary Uses of Data

*Blog post

Year 2004

Privacy in research

Mark Barnes gave a seminar on August 2, 2004 on Secondary Uses of Biologic Materials and Medical Data by Researchers and Commercial Research Sponsors. Here are my notes…

Breaking the blind

*Blog post

Year 2004

Blinding in research

Someone asked an interesting question on the IRBForum today. Under what circumstances should the blinding for a trial be broken when an unexpected Serious Adverse Event…

Statalist

*Blog post

Year 2004

Statistical computing

I recently upgraded to version 8 of Stata, which is a nice program for advanced statistical analyses. During the registration of the software, the program asked me if I…

Evaluating the AUC for an ROC curve

*Blog post

Year 2004

Diagnostic testing

Someone asked me where I got the following guidance for Area Under the Curve (AUC) for a Receiver Operating Characteristic (ROC) curve.

Confidence intervals for proportions

*Blog post

Year 2004

Confidence intervals

One of the fellows at the hospital asked me about confidence intervals for proportions. I wrote a couple of simple spreadsheets to do these calculations

Random identification numbers

*Blog post

Year 2004

Randomization

Someone asked me today for a set of random numbers. The purpose was to create an ID code that could be used to track back to the original records to resolve any…

Sample size calculations in studies with a baseline

*Blog post

Year 2004

Sample size justification

Many research studies evaluate all patients at baseline and then randomly assign the patients to groups, conduct the interventions, and then re-evaluate them at the end of…

Is there a mechanism?

*Blog post

Year 2004

Corroborating evidence

“Extraordinary claims require extraordinary proof.” This is the mantra of skeptical thinkers and it provides useful for evaluating claims that fall outside the mainstream of…

Retrospective chart reviews and IRB approval

*Blog post

Year 2004

Privacy in research

Someone stopped by today with a question about getting IRB approval for a retrospective chart review. They were interested in examining the efficacy of a certain drug that…

Conflict of interest

*Blog post

Year 2004

Conflict of interest

Does having a commercial interest in the results of a drug trial cause a problem for the people running the trial? If it does, then much of the research that we rely on…

Aliasing patterns

*Blog post

Year 2004

Statistical computing

When you draw lines and curves on a computer screen, most of them end up with a subtle staircase pattern because you are using discrete pixels to represent a smooth line or…

Bluejacket Toastmasters Speech

*Blog post

Year 2004

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Bluejacket Toastmasters speech

*Blog post

Year 2004

Presenting research

This is the text of a talk I gave to Bluejacket Toastmasters on July 15, 2004.

Adaptive randomization

*Blog post

Year 2004

Equipoise in research

Randomization

Someone on the IRBForum posed a theoretical question. Is running a three arm study troublesome from an ethical viewpoint because the probability that any subject in the…

Randomization test

*Blog post

Year 2004

Unusual data

I received some data from a project where the outcome measure was the degree of improvement after a treatment, with values of -1 (slight decline), 0 (no change), 1 (slight…

Provisional means algorithm

*Blog post

Year 2004

Statistical computing

One of the new fellows asked me about a data summary for two groups of patients. The ages were quite different, the mean age was 4.6 years in the exposure group and 8.5…

Testing for side effects

*Blog post

Year 2004

Being updated

Testing for side effects

*Blog post

Year 2004

Being updated

Planning a qualitative research study

*Blog post

Year 2004

Qualitative research

Someone asked me for some specific advice on how to design a qualitative study. I love qualitative research. I think people should be using this mode of research more often.…

Sample size for a diagnostic test

*Blog post

Year 2004

Sample size justification

Someone asked me how to determine the sample size for a study involving a diagnostic test. It seems like a tricky thing, because most studies of diagnostic tests don’t have…

Early stopping in an animal study

*Blog post

Year 2004

Early stopping

Rmarkdown code

I was helping someone with power calculations for an animal experiment. There were several ways to estimate power and they all seemed to point to the use of either 8 animals…

Lost page

*Blog post

Year 2004

Being updated

Earlier versions are here and here.

Small relative risk

*Blog post

Year 2004

Corroborating evidence

Someone asked me about small relative risk. It was only 1.12, but because of the large sample size, it was still statistically significant. This person wanted to discount…

Nonlinear Least Squares in S-plus and R

*Blog post

Year 2004

Nonlinear regression

I’ve worked on a brief explanation of how to fit an S-shaped curve using SPSS and someone wanted to know how to do this in R.

Excluding placebo responders

*Blog post

Year 2004

Exclusions in research

Placebos in research

I’ve always been fascinated by the placebo effect and the ethical issues associated with use of placebos in research.

Publication bias

*Blog post

Year 2004

Publication bias

Eliot Spitzer, New York’s state attorney general has filed a lawsuit against GlaxoSmithKline for concealing negative trials about an antidepressant that the company…

Pap smears for women without a cervix

*Blog post

Year 2004

Diagnostic testing

In the most recent issue of JAMA is an article by Sirovich and Welch, Cervical Cancer Screening Among Women Without a Cervix [Abstract] that estimates almost 10 million…

Lost page

*Blog post

Year 1999

Being updated

You can find an earlier version of this page on my website.

The impact of XML on Statistics

*Blog post

Year 2004

Statistical computing

XML (eXtensible Markup Language) is standard for sorting information that has the flexibility needed to handle complex data. It is similar to HTML (HyperText Markup…

Missing values

*Blog post

Year 2004

Statistical theory

Someone here at the hospital asked me how to do a reliability analysis on a 20 item measure where a large number of participants left a single item blank. There are several…

McNemar’s Test

*Blog post

Year 2004

Unusual data

I received an email asking how to test two correlated proportions to see if one proportion is significantly larger than another. This is a classic application of McNemar’s…

Data Mining with Clementine

*Blog post

Year 2004

Data mining

Statistical computing

I attended an SPSS web seminar about their Clementine program, which performs data mining. The talk was oriented to business applications, but still had some interesting…

Evidence-based Complementary and Alternative Medicine

*Blog post

Year 2004

Teaching resources

There’s a new journal out with free full text on the web. It is Evidence-based Complementary and Alternative Medicine and is published by Oxford Journals online. I find that…

Statistical consulting

*Blog post

Year 2004

Teaching resources

Most training programs in Statistics do a good job in emphasizing the various tools that you will need, but it is much harder to teach the nonstatistical aspects of…

Categorical variables in a logistic regression model

*Blog post

Year 2004

Logistic regression

On April 8, I had written a brief description of interactions in a logistic regression model. This was a supplement to a discussion of the concepts behind the logistic…

Monte Carlo methods

*Blog post

Year 2004

Statistical computing

I got a question from someone in my office who is taking a class on research methods. She asked me to define the term “Monte Carlo” that her teacher had used without much of…

Health effects of smoking

*Blog post

Year 2004

Corroborating evidence

A recent Surgeon’s General report on smoking adds new cause-and-effect links between smoking and several diseases including cataracts, pneumonia, acute myeloid leukemia…

What is information theory

*Blog post

Year 1999

Being updated

Information theory

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Analyzing percentage data

*Blog post

Year 2004

Unusual data

I received one of those difficult to answer questions: how do I analyze my data when the outcome variable is a percentage. That depends a lot on the context of the problem.

Sample size calculation example

*Blog post

Year 2004

Sample size justification

I received a question in Hong Kong about how to double check a power calculation in a paper by Tugwell et al in the 1995 NEJM.

Goodness of fit test

*Blog post

Year 2004

Measuring agreement

The chi-square test appears in a lot of different places. Some recent data on Astrology, published in the May newsletter of the Skeptic Society, offers an interesting…

Correlations with categorical variables

*Blog post

Year 2004

Descriptive statistics

I got another question, this one from Brooklyn, New York. It’s a commonly asked question, so I should write something about this. The question is whether you can get a…

Sample size for a survival data model

*Blog post

Year 2004

Sample size justification

I got an email from Japan recently with an interesting question. By the way, one of the fun things about my web pages is that I get emails from all over the world. I can…

Advanced SPSS methods

*Blog post

Year 2004

SPSS software

SPSS had a nice web seminar on their Regression and Advanced Statistics modules. Here are some notes that I took while sitting in.

Information Theory Models

*Blog post

Year 2004

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Information Theory Examples

*Blog post

Year 2004

Being updated

The formula for uncertainty (sometimes referred to as entropy) is

Notes from JSM 2004

*Blog post

Year 2004

Being updated

This page is crrently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Response to Olshansky and Dossey

*Blog post

Year 2004

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Information Theory

*Blog post

Year 2004

Being updated

Information theory

The formula for uncertainty (sometimes referred to as entropy) is

Acuity microarray analysis software.

*Blog post

Year 2004

Data mining

Statistical computing

I got a request to evaluate some software by Axon Instruments for the analysis of microarray data. The software, Acuity version 3.1, costs $4,000 per person and has to…

Overlooking one’s own flaws

*Blog post

Year 2004

Critical appraisal

Can we ever be truly objective about ourselves? Maybe not. A recent article in Scientific American by Michael Shermer, The Enchanted Glass, talks about the tendency to see…

Degrees of freedom, Part 2

*Blog post

Year 2004

Statistical theory

I received an email inquiry about degrees of freedom. I explain the concept briefly, but this person wanted a more detailed answer to the question, why do we use n-1 in the…

The Wikipedia

*Blog post

Year 2004

Teaching resources

Part of my job on these web pages is to find good resources beyond what I can write about Statistics. I’m finding more and more that there are wonderful references in a web…

Focus groups and qualitative research

*Blog post

Year 2004

Qualitative research

A student is giving a talk on focus groups and asked me a few questions about my attitude towards them. I think focus groups are great. They give you a richer picture of the…

Clinically trivial effects

*Blog post

Year 2004

Clinical importance

I don’t like to cite articles in the New York Times, because they are free on the web only for a couple of weeks. But an article by Denise Grady, Nominal Benefits Seen in…

One-tailed p-values

*Blog post

Year 2004

Hypothesis testing

Someone asked me how to compute one-sided p-values in SPSS. The output from SPSS always uses two-sided p-values. This was worth an explanation, so I added a new question to…

One tailed p-values

*Blog post

Year 2004

Pvalues

Dear Professor Mean, SPSS produces two-tailed p-values, but I want a one-tailed p-value. How do I get this?

A serious problem of publication bias

*Blog post

Year 2004

Publication bias

I was browsing a paper by Leonard Leibovici [Medline] about alternative medicine when a comment by Andrew Vickers in the eletters section caught my eye. He noted the serious…

Interactions in logistic regression

*Blog post

Year 2004

Logistic regression

Someone asked me how to compute interactions in binary logistic regression. You need to be careful, since interactions are tricky to interpret. I need to update my pages to…

Temporality of Causes

*Blog post

Year 2004

Corroborating evidence

One of the nine criteria that Sir Austin Bradford Hill offers to establish a cause and effect relationship is temporality. In order for A to cause B, A must precede B in…

Constraints on Randomization

*Blog post

Year 2004

Randomization

I received an inquiry from our Institutional Review Board about a study they were doing a continuing review for. This was a non-randomized comparison of two surgical…

Evidence-based lessons learned from Cardiology

*Blog post

Year 2004

Teaching resources

There was a nice series of articles in the journal Circulation that appeared in 2002 with free full text online. These articles offer specific lessons about evidence-based…

Steps in a typical microarray analysis

*Blog post

Year 1999

Being updated

Data mining

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

EM Algorithm

*Blog post

Year 2004

Statistical computing

I received an email question about the EM Algorithm. This is a computational approach that works well for missing data problems and data models with latent (unobserved)…

Steps for establishing a quality control program

*Blog post

Year 2004

Quality control

So you’ve decided to implement a quality control program in your laboratory. What will it take to make that program successful? There are three steps, and you must follow…

Steps for establishing a quality control program

*Blog post

Year 1999

Being updated

Quality control

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Central Limit Theorem

*Blog post

Year 2004

Modeling issues

Dear Professor Mean, How does the central limit theorem affect the statistical tests that I might use for my data?

Quality control in the laboratory

*Blog post

Year 2004

Quality control

I’ll be giving a talk at the American Society for Andrology in April about the use of quality control for sperm morphology assessments. I’ll put some of my notes up on the…

Parametric versus nonparametric tests

*Blog post

Year 2004

Unusual data

One of the biggest areas of disagreement among statisticians is when to use parametric or non-parametric statistics. I got an inquiry about this today, and quite honestly, I…

Conflict of Interest

*Blog post

Year 2004

Conflict of interest

The New York Review of Books has a extensive review written by Richard Horton of the book Science in the Private Interest: Has the Lure of Profits Corrupted Biomedical…

Evidence Based Medicine and Ethics

*Blog post

Year 2004

Teaching resources

The Journal of Medical Ethics has a series of articles about ethics and evidence based medicine. These are pre-prints of articles under review and you can prepare a response…

Number needed to harm examples

*Blog post

Year 2004

Measuring benefit and risk

I was trying to track down a reference on the NNH (number needed to harm) for antibiotic use, but noticed instead the large number of good examples of NNH calculations in…

S-shaped curves

*Blog post

Year 2004

Nonlinear regression

Competitive binding experiments will often need a nonlinear regression model. This model has to level off at both extremes to represent almost no binding at one end and…

Enumerative and Analytic Studies

*Blog post

Year 2004

Descriptive statistics

Research design

I received a question today via email about what statistics you can use when your sample equals the entire population. This issue also comes up when people ask about the use…

Educational Resources

*Blog post

Year 2004

Teaching resources

Someone posed a question on the IRB Discussion forum wondering if there was a source of free materials “that we can email or distribute as hardcopy to our study coordinators…

Brief Biography

*Blog post

Year 2004

Professional details

Steve Simon earned a Ph.D. in Statistics from the University of Iowa in 1982. He currently works as a research biostatistician at Childrens Mercy Hospitals and Clinics in…

Steps in establishing validity/reliability

*Blog post

Year 1999

Being updated

Measuring agreement

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Craniosacral therapy

*Blog post

Year 2004

Being updated

In vitro fertilization prayer study

*Blog post

Year 2004

Being updated

What’s a good value for Cronbach’s Alpha?

*Blog post

Year 2004

Being updated

Deaf chairs, lost cake recipes, and a letter from Maria.

*Blog post

Year 2004

Being updated

I hate PowerPoint

*Blog post

Year 2004

Being updated

Weblog entries from the 2004 JSM

*Blog post

Year 2004

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

In vitro fertilization prayer study

*Blog post

Year 2004

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

My efforts to kill PowerPoint

*Blog post

Year 2004

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Recent updates

*Blog post

Year 2004

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Steps in a typical equivalence data analysis

*Blog post

Year 2003

Hypothesis testing

Incomplete page

There are three approaches that are used to demonstrate equivalence, each with its advantages and disadvantages.

Accuracy of computations

*Blog post

Year 2003

Statistical computing

I’ve heard a lot about accuracy problems with Microsoft Excel, but I’d like to see an example where this really is a problem.

Data is/are

*Blog post

Year 2003

Broken link

Writing research papers

Should I write “data is” or “data are”?*

A simple model of nonlinear growth

*Blog post

Year 2003

Nonlinear regression

Part of the challenge in nonlinear regression is to choose the correct form of the nonlinear relationship. Part of this is intuition, part of this is understanding some…

Steps in a typical data mining model

*Blog post

Year 2003

Broken link

Data mining

Incomplete page

I’m not an expert on data mining, but I wanted to outline some of the basic issues associated with data mining problems. This material is based largely on notes that I took…

An introduction to diagnostic testing

*Blog post

Year 2003

Being updated

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

SPSS syntax for Poisson Regression, Marta Garcia-Granero, PhD

*Blog post

Year 2003

Poisson regression

Obsolete page

Note: you can now run Poisson regression directly from the SPSS menus, so this syntax is no longer needed. I am keeping it here because I am an electronic packrat.

Mean or median?

*Blog post

Year 2003

Descriptive statistics

I am writing a report on turnover. I want to summarize the number of weeks it takes to fill a vacancy. Should I use a mean or a median?

What does “overfitting” mean?

*Blog post

Year 2003

Modeling issues

I am conducting binary logistic regression analyses with a sample size of 80 of which 20 have the outcome of interest (e.g. are “very successful” versus somewhat/not very…

Steps in a typical ANOVA model

*Blog post

Year 2003

Analysis of variance

I wanted to compare two groups in my research, those who completed every test battery, and those who completed only some of them. I ran ANOVAs on age, iq, adhd score, and so…

Pitch the pie! Ban the bar!

*Blog post

Year 2003

Descriptive statistics

Graphical display

This is an outline of a speech that I gave to Bluejacket Toastmasters on June 5, 2003.

Skewed data

*Blog post

Year 2003

Descriptive statistics

Please explain how the standard deviation can be greater than the mean. I think it is because of skewed data.*

Cluster randomization

*Blog post

Year 2003

Sample size justification

One of my favorite people to work with, Vidya Sharma, was asking me how to compute the sample size in a cluster randomized trial. I had started to write a web page about…

Cluster randomization

*Blog post

Year 2003

Sample size justification

One of my favorite people to work with, Vidya Sharma, was asking me how to compute the sample size in a cluster randomized trial. I had started to write a web page about…

Maximum likelihood estimation

*Blog post

Year 2003

Statistical theory

What is maximum likelihood estimation and how does it work?*

Maximum likelihood estimation

*Blog post

Year 2003

Statistical theory

Dear Professor Mean, What is maximum likelihood estimation and how does it work?

Obsolete! CMH Consulting Services

*Blog post

Obsolete page

Year 2003

Professional details

This page is obsolete, but I am keeping it around because I am an electronic pack rate.

Why informed consent is important

*Blog post

Year 2003

Ethics in research

To understand why researchers today must obtain informed consent from their patients before they subject them to experiments, you need to understand some of the previous…

Building a complex model

*Blog post

Year 2003

Linear regression

When you have a lot of variables that might possibly influence your outcome, your desire is to find some automated procedure that will select your model for you. Using an…

Coding race/ethnicity

*Blog post

Year 2003

Broken link

Data management

If you have to collect data on the race and/or ethnicity of your research subjects, you should be aware of the official U.S. government definitions that all federal agencies…

Diagnostic

*Blog post

Year 2003

Website details

This page provides resources for a small booklet I have developed, “An introduction to diagnostic testing.” I have printed a few of these booklets and attached a fully…

Displaying tables of percentages

*Blog post

Year 2002

Ask Professor Mean

Descriptive statistics

Writing research papers

Dear Professor Mean, My colleagues and I argue over the most appropriate way for displaying tables of percentages. Must the row or column always add to 100%? Also in cases…

Post hoc power

*Blog post

Year 2002

Post hoc power

Dear Professor Mean, The results of my study were negative, and the journal reviewer insists that I perform a post hoc power calculation. How do I do this? -Jittery Jerry

Likelihood ratio slide rule

*Blog post

Year 2008

Being updated

Likelihood ratio slide rule

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Log transformation

*Blog post

Year 2002

Ask Professor Mean

Modeling issues

Dear Professor Mean, I have some data that I need help with analysis. One suggestion is that I use a log transformation. Why would I want to do this?

Steps in a typical survival data analysis

*Blog post

Year 2002

Survival analysis

There are three steps in a typical survival analysis.

Getting IRB approval for your research

*Blog post

Year 2002

Incomplete page

Ethics in research

Dear Professor Mean:

Checking the assumption of normality

*Blog post

Year 2002

Ask Professor Mean

Modeling issues

Dear Professor Mean, I have some data that don’t seem to meet the assumption of normality. What should I do?

Data management for survival data

*Blog post

Year 2002

Being updated

Survival analysis

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Exploring interactions in a linear regression model

*Blog post

Year 2002

Ask Professor Mean

Linear regression

Dear Professor Mean, I have a model with two factors. When I ran the model, it showed a significant interaction between the two factors. What do I do now?

Longitudinal data

*Blog post

Year 2002

SPSS software

Dear Professor Mean, I have longitudinal data on the growth pattern of patients given growth hormone. How should I store the data? –Jittery Jerry

The concepts behind the logistic regression model

*Blog post

Year 2002

Incomplete page

Logistic regression

The logistic regression model is a model that uses a binary (two possible values) outcome variable. Examples of a binary variable are mortality (live/dead), and morbidity…

SPSS dialog boxes for logistic regression

*Blog post

Year 2002

Logistic regression

This handout shows some of the dialog boxes that you are likely to encounter if you use logistic regression models in SPSS.

Privacy concerns in research

*Blog post

Year 2002

Ask Professor Mean

Privacy in research

Dear Professor Mean, I want to do some research using tissue samples, but the Institutional Review Board has said that I have to get consent first, because the data are not…

So you want to write a questionnaire

*Blog post

Year 2002

Survey design

Dear Professor Mean, I need to write a questionnaire for a research study I am conducting. Can you help me write it? – Cautious Carmen

Interpreting coefficients in a linear regression model

*Blog post

Year 2002

Linear regression

When I ask most people to remember their high school algebra class, I get a mixture of reactions. Most recoil in horror. About one in every four people say they liked that…

Interpreting coefficients in a linear regression model

*Blog post

Year 1999

Being updated

Earlier versions are here and here.

SPSS dialog boxes for a descriptive analysis

*Blog post

Year 2002

Descriptive statistics

This handout will show the SPSS dialog boxes that I used to create the examples in the descriptive data analysis handout. I will capitalize variable names, field names and…

SPSS dialog boxes for linear regression models

*Blog post

Year 2002

Linear regression

This handout will show the SPSS dialog boxes that I used to create linar regression examples. I will capitalize variable names, field names and menu picks for clarity.

Why 95% confidence limits?

*Blog post

Year 2002

Ask Professor Mean

Confidence intervals

Dear Professor Mean, I’ve been working with small data sets for some neuroimaging research that have 5 treatment and 5 control participants. It is not unusual to have such…

SPSS citation

*Blog post

Year 2002

Ask Professor Mean

SPSS software

Dear Professor Mean, I’m writing a research paper. When I talk about the statistical methods, how do I properly cite the use of SPSS software? And just what does SPSS stand…

Biography

*Blog post

Year 2002

Professional details

Steve Simon earned a PhD in Statistics from the University of Iowa in 1982. His training emphasized applied statistics and he served for two years as the student head of the…

Stopping a study early

*Blog post

Year 2002

Website details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Establishing validity and reliability

*Blog post

Year 2002

Ask Professor Mean

Incomplete page

Measuring agreement

Dear Professor Mean, I need to establish validity and reliability of a new measurement. How do I do this?

Statistical Training Opportunities At Children’s Mercy Hospital

*Blog post

Year 2008

Obsolete page

This page is obsolete. I am keeping it around mostly for nostalgic reasons.

Unequal group sizes

*Blog post

Year 2001

Being updated

Analysis of variance

Dear Professor Mean, I am comparing several groups of subjects, but the number of subjects in each group differ quite a bit. How does this affect the assumptions in analysis…

BMJ letter

*Blog post

Year 2001

Being updated

Randomization in research

Here’s a letter I submitted to the web letters to the editor for the British Medical Journal in response to an article about randomisation (BMJ 1999 Sep 11;319(7211):703-704).

Problems with a very small sample

*Blog post

Year 2001

Being updated

Small sample size issues

Dear Professor Mean, Are there problems with a very small sample? Can the t-test be used with a sample of just three subjects? – Anxious Abdelwahab

Steps in a descriptive model

*Blog post

Year 2001

Being updated

Descriptive statistics

Every data analysis should start with a descriptive or exploratory analysis. If you have no research hypotheses, then you can stop with this. If you do have research…

Parametric versus nonparametric tests

*Blog post

Year 2001

Being updated

Unusual data

Dear Professor Mean, When should I use a parametric test versus a non-parametric test?

Web polls

*Blog post

Year 2001

Being updated

Research design

Dear Professor Mean, I’m conducting a number of web-based polls and would like to include a margin of error in my results. How do I do this?

Loading ODBC drivers from the Microsoft Data Access Pack

*Blog post

Year 2001

Being updated

Data management

SPSS software

This page is obsolete, but I am keeping it here for sentimental reasons.

The minimal impact of population size on power and precision

*Blog post

Year 2001

Confidence intervals

Rmarkdown code

Sample size justification

Can you explain why it is okay to have similar sample sizes for populations of very different sizes. For example, why is it that a sample size for a population of 10 million…

Confidence interval with zero events

*Blog post

Year 2005

Confidence intervals

Dear Professor Mean, I was working with a colleague on some confidence intervals for the probability of an adverse event during several different types of operations. One of…

Writing the methods section of your grant

*Blog post

Year 2001

Being updated

Incomplete page

Writing research grants

Dear Professor Mean, I’m starting to write the methods section for a research grant, but I have no idea where to start. – Dazed Dana

Odds ratio versus relative risk

*Blog post

Year 2001

Being updated

Measuring benefit and risk

Dear Professor Mean: There is some confusion about the use of the odds ratio versus the relative risk. Can you explain the difference between these two numbers?

Documenting negative results in a research paper

*Blog post

Year 2001

Being updated

Website details

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Ethics of a placebo group

*Blog post

Year 2001

Being updated

Website details

Dear Professor Mean, Some of my colleagues want to use placebos in their research, but I have warned them about the ethical issues surrounding the use of a placebo group.…

Quick sample size calculations

*Blog post

Year 2001

Being updated

Website details

Dear Professor Mean, I’m reading a research paper. I suspect that the sample size is way too small. I don’t like the findings of the study anyway, so I’m hoping that you…

Three things you need for a power calculation

*Blog post

Year 2001

Being updated

Website details

Dear Professor Mean, I want to do research. Is forty subjects enough, or do I need more? Eager Edward

*Blog post

Year 2000

Incomplete page

Quality improvement

This page is being updated.

*Blog post

Year 2000

Quality improvement

This page is being updated.

*Blog post

Year 2000

Quality improvement

This page is being updated.

*Blog post

Year 2000

Quality improvement

This page is being updated.

Protocol changes.

*Blog post

Year 2000

Early stopping

Dear Professor Mean, After I collected my data, I noticed a problem that I had not anticipated. I want to make some protocol changes and analyze my data differently. Can I…

Sample size for the Mann-Whitney U test

*Blog post

Year 2000

Sample size justification

Dear Professor Mean, I need to calculate the sample size for the Mann-Whitney U test. How do I do this? – Bewildered Bob

Software used to create these web pages.

*Blog post

Year 2000

Obsolete page

Website details

This page is obsolete. I am keeping it around mostly for nostalgic reasons.

Binary outcome sample size calculations

*Blog post

Year 2000

Being updated

Sample size justification

*Dear Professor Mean, I have to calculate a sample size for a binary outcome variable. The research study is on breast feeding failures within 7 to 10 days of birth for…

Stratified random sample.

*Blog post

Year 2000

Ask Professor Mean

Research design

Dear Professor Mean, What is a stratified random sample and why would I want to use one?

Fisher’s Exact Test

*Blog post

Year 2000

Logistic regression

Dear Professor Mean, What is Fisher’s Exact Test and when should I use it?

Alternating treatments

*Blog post

Year 2000

Ask Professor Mean

Randomization

Dear Professor Mean, I’m running an experiment where I randomize by alternating between the treatment and the control. I was told this is not the proper way to do this. Why…

What is the Kaplan Meier curve?

*Blog post

Year 2000

Ask Professor Mean

Survival analysis

Dear Professor Mean, When I read my medical journals, I keep on coming across terms like Kaplan-Meier Product Limit estimate or Kaplan-Meier survival curve. What do these…

Links from other sites

*Blog post

Year 2000

Website details

Website details

It’s flattering when someone recommends my site, so I keep track of this here. I also want to keep tabs on these links so when I change a page name, I am sure that it…

Acknowledgements

*Blog post

Year 2000

Website details

These web pages have several Sherlock Holmes quotes. These quotes can be found in the marvelous book Statistically Speaking. A Dictionary of Quotations, by C.C. Gaither and…

Copyright notice

*Blog post

Year 2000

Website details

This page is obsolete and is being included only for historical purposes. The proper copyright notice is included in the footer for every page.

Exporting SPSS graphs and tables.

*Blog post

Year 2000

Data management

SPSS software

Dear Professor Mean, I need to export the output from SPSS and use some of it in my word processing file. What is the best way to do this? – Manic Marsha

Important disclaimer.

*Blog post

Year 2000

Website details

Although I work in a hospital, my profession is Statistics. I help the doctors and nurses here plan research studies and make sense of the numbers after the research is done. …

Quota stratified random sampling.

*Blog post

Year 2000

Ask Professor Mean

Research design

Dear Professor Mean, I’m doing my thesis right now and I have to use quota stratified random sampling. I do not know the exact meaning of this term.

Outliers

*Blog post

Year 2000

Ask Professor Mean

Unusual data

Dear Professor Mean, I have recently conducted a survey of attitudes toward research from a professional group. There are some outliers (+/- 3SD) that I would eliminate …

Spreadsheet or Database?

*Blog post

Year 2000

Ask Professor Mean

Data management

Dear Professor Mean, I am not sure whether I should use a database or a spreadsheet to enter my data?

Association versus causation

*Blog post

Year 2000

Ask Professor Mean

Corroborating evidence

Dear Professor Mean, Everyone says that smoking causes cancer, but we can’t really say that, can we? There is an association between smoking and cancer, but we know that…

Composite scores

*Blog post

Year 2000

Unusual data

I have developed a method to distinguish among several products that we need to buy so our company can make a good purchasing decision. I created a composite score which is…

Sigma in the control chart.

*Blog post

Year 2000

Ask Professor Mean

Control charts

Dear Professor Mean, I ran a control chart in SPSS for individual values, and the control limits don’t correspond with what I would expect from the descriptive procedure…

Physician Performance Data

*Blog post

Year 2000

Unusual data

Dear Professor Mean, Producing statistics of physician performance or group performance or whatever seems to be one of the great growth industries in medicine. Graphs of…

Regression to the mean

*Blog post

Year 2000

Ask Professor Mean

Linear regression

Dear Professor Mean, In a stat course I was introduced to the term “regression to the mean”. Today we administered a pretest to 4th graders. In Feb we will again test, with…

Flaws in a research paper

*Blog post

Year 2000

Critical appraisal

Dear Professor Mean, A small group I’ve been teaching has gotten extremely interested in how to decide when there are too many flaws in a paper which would completely…

Jargon in Statistics

*Blog post

Year 2000

Ask Professor Mean

Critical appraisal

Dear Professor Mean, I have to review a paper for journal club and I don’t understand all the obscure statistical jargon that the authors use.

Bootstrap

*Blog post

Ask Professor Mean

Year 2000

Unusual data

Dear Professor Mean, I’ve heard a lot about how the bootstrap is going to revolutionize Statistics.

What is collinearity?

*Blog post

Year 2000

Ask Professor Mean

Modeling issues

Dear Professor Mean, Could you describe the term collinearity for me? I understand that it has to do with variables which are not totally independent, but that is all I know!

Intention to treat

*Blog post

Year 2000

Ask Professor Mean

Measuring benefit and risk

Dear Professor Mean, I’m confused by medical journal articles that talk about the use of “Intention to Treat” analysis. What does this term mean?

Mixture models

*Blog post

Year 2000

Ask Professor Mean

Unusual data

Dear Professor Mean, I have read a journal article where the authors used a mixture model . What is this?

Number Needed to Treat

*Blog post

Year 2000

Ask Professor Mean

Measuring benefit and risk

Dear Professor Mean, How are patients and their doctors supposed to decide whether a research finding has practical significance? Why don’t the medical journals make things…

Splines

*Blog post

Year 2000

Ask Professor Mean

Unusual data

Dear Professor Mean, Can you send me a basic definition of splines?

Stein’s paradox

*Blog post

Year 2000

Being updated

Statistical theory

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Best fitting curve

*Blog post

Year 2000

Ask Professor Mean

Modeling issues

Dear Professor Mean, I have a graph of the trend for the mean frequency of injuries among children from 1 to 11 years of age. The shape of the curve suggests a nonlinear…

Sample size for a confidence interval

*Blog post

Year 2000

Ask Professor Mean

Confidence intervals

Sample size justification

Dear Professor Mean, We have a large dataset with about 400 million records. We need to randomly select a subsample from it. However we need help in determining the sample…

Copyright

*Blog post

Year 2000

Obsolete page

Website details

This page is obsolete. My pages on the current website are placed into the public domain. I am keeping this page around mostly for nostalgic reasons.

Future work on this website

*Blog post

Year 2000

Website details

This page is obsolete. I am keeping it around mostly for nostalgic reasons.

Obsolete webpages

*Blog post

Year 2000

Website details

This page is being phased out. Look for the obsolete page tag on my new website.

Information about myself

*Blog post

Year 2000

Professional details

This page is obsolete, but I am keeping it around mostly for nostalgic reasons.

My resume

*Blog post

Year 2000

Professional details

This page is obsolete. I am keeping it around mostly for nostalgic reasons.

Circular data models

*Blog post

Year 1999

Being updated

Circular data

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Meta-analysis for a diagnostic

*Blog post

Year 1999

Being updated

Diagnostic testing

There is no real consensus yet on how to best combine data from several studies of a diagnostic test. I will outline a few approaches that seem to make sense.

Meta-analysis for a diagnostic

*Blog post

Year 1999

Being updated

Diagnostic testing

There is no real consensus yet on how to best combine data from several studies of a diagnostic test. I will outline a few approaches that seem to make sense. In addition to…

Longitudinal data analysis

*Blog post

Year 1999

Being updated

Multilevel models

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Guidelines for logistic regression models

*Blog post

Year 1999

Being updated

Logistic regression

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Injury index creation

*Blog post

Year 1999

Unusual data

Dear Professor Mean, I want to create an injury index that describes the severity of an injury to a child. This would include information about the type of injury, the…

Steps in a typical linear regression analysis

*Blog post

Year 1999

Being updated

Linear regression

Let no man ignorant of geometry enter - Sign over Plato’s Academy in Athens

Poisson regression model

*Blog post

Year 1999

Being updated

Poisson regression

Dear Professor Mean, I have just received feedback on a manuscript under review in which one reviewer recommended use of Poisson regression. I am not familiar with this…

Importing spreadsheet data into SPSS

*Blog post

Year 1999

Being updated

Data management

SPSS software

Dear Professor Mean, I need to import data in an Excel spreadsheet, but I can’t get SPSS to read this data properly. Can you help? – Stumped Stan

Where do research ideas come from? by Ronan Conroy

*Blog post

Year 1999

Being updated

Grant writing

This is an HTML format version of an email by Ronan Conroy on April 9, 1999 to edstat-l, an Internet list and to sci.stat.edu, a USENET group. This email summarized a…

Documenting your SPSS data sets

*Blog post

Year 1999

Being updated

Data management

SPSS software

Dear Professor Mean, I need to add some documentation for SPSS data sets that I am creating. I know you covered this in your “Gentle Introduction to SPSS” class, but I’ve…

Modifying SPSS data

*Blog post

Year 1999

Being updated

Data management

SPSS software

Dear Professor Mean, Before I start my data analysis, I need to modify some of the data in my SPSS data set. I don’t want to re-type every number by hand. Is there a faster…

Inputting a two-by-two table into SPSS

*Blog post

Year 1999

Being updated

Data management

SPSS software

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Writing a research grant

*Blog post

Year 1999

Being updated

Grant writing

Dear Professor Mean, I’m writing a research grant to look at the impact of managed care on the care of children with chronic epilepsy. How do I structure the grant so I’m…

Interim analysis

*Blog post

Year 1999

Being updated

Early stopping

Dear Professor Mean, I’m going on a job interview and I know one of the questions they will ask me is about interim analysis. What should I tell them? -- Harried Howard

Type II error

*Blog post

Year 1999

Being updated

Hypothesis testing

Dear Professor Mean, A journal reviewer criticized the small sample size in my research study and suggested that I mention a Type II error as a possible explanation for my…

Asymmetric confidence intervals

*Blog post

Year 1999

Being updated

Confidence intervals

Dear Professor Mean, I found a journal article with a confidence interval that was asymmetric. For example, the authors reported a mortality difference of 5% and a 95%…

Sample size for a diagnostic study

*Blog post

Year 1999

Being updated

Confidence intervals

Diagnostic testing

Sample size justification

Dear Professor Mean, How big should a study of a diagnostic test be? I want to estimate a sample size for the sensitivity and specifity of a test. I guess confidence…

General guide to data entry

*Blog post

Year 1999

Being updated

Data management

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Pilot study

*Blog post

Year 1999

Being updated

Ask Professor Mean

Pilot studies

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Bonferroni correction

*Blog post

Year 1999

Being updated

Multiple comparisons

Dear Professor Mean, I keep reading about something called a Bonferroni correction. Somehow this method keeps researchers from going on a fishing expedition. Could you…

Chi-squared test

*Blog post

Year 1999

Being updated

Unusual data

Dear Professor Mean, Can the Chi-square test be used for anything besides categorical data?

Degrees of Freedom

*Blog post

Year 1999

Being updated

Statistical theory

Dear Professor Mean, In your Simple Descriptive Statistics class, you described the standard deviation as the square root of the average squared deviation. If it is an…

E notation

*Blog post

Year 1999

Being updated

Writing research papers

Dear Professor Mean, In my regression output, I saw that following value: -2.384E-03. What does this E notation mean?

Page’s test

*Blog post

Year 1999

Being updated

Unusual data

Dear Professor Mean, I have recently come across a statistical test (Page’s L test),with which I am unfamiliar. Does anyone either have information about this test or know…

ROC curve

*Blog post

Year 1999

Being updated

Diagnostic testing

Dear Professor Mean, I was at a meeting in Belgium and the buzz statistic was ROC Analysis. I think it stands for Receiver Operating Characteristic curve. It seems to be…

All or nothing

*Blog post

Year 1999

Being updated

Small sample size issues

This page is currently being updated from the earlier version of my website. Sorry that it is not yet fully available.

Date calculations in SPSS

*Blog post

Year 1999

Being updated

Data management

SPSS software

Dear Professor Mean, I am trying to use dates in SPSS for certain calculations. For example, I want to use a compute statement in SPSS to create a new variable called…

Importing database files into SPSS

*Blog post

Year 1999

Being updated

Data management

SPSS software

Note: many of the details described here, may have changed. Every new version of SPSS and of Microsoft Windows makes small and sometimes large changes to the approach…

Developing a research hypothesis

*Blog post

Year 1999

Being updated

Grant writing

Dear Professor Mean, I want to do some research, but before the hospital won’t approve anything until I have a protocol with a research hypothesis. I’m not sure why a…

How to randomize

*Blog post

Year 1999

Being updated

Randomization

Dear Professor Mean, I need to randomize the order in which I give treatments and controls in my research study, but I don’t know how to randomize. Can you show me what to…

R-squared

*Blog post

Year 1999

Being updated

Linear regression

Dear Professor Mean, On my TI-83, when calculating quadratic regression, there is a number that is found called R-squared (R^2). I understand that this is the coefficient of…

T-test

*Blog post

Year 1999

Hypothesis testing

Dear Professor Mean, How do you analyze a t-test. I have a t-test value, and I know that I have to compare it to a t-distribution. I’m not sure how to do that.

Merging files in SPSS

*Blog post

Year 1999

Being updated

Data management

Ask Professor Mean

SPSS software

Dear Professor Mean, I get a strange error message when I try to merge two files in SPSS. What is going on? – Computing Cheryl