StATS: Interesting web sites, publications, and quotes for the month of August (August 31, 2005) Category: Interesting stuff

Note: any quotations on this page have been moved to Category: Interesting quotes.

On uncertainty in medical testing. Winkler RL, Smith JE. Med Decis Making 2004: 24(6); 654-8. [Medline]

There is confusion in the medical decision-making literature about how to handle uncertainty in medical tests. In this article, the authors consider the situation in which there is uncertainty about the pretest probability of a disease in a patient as well as uncertainty about the sensitivity and specificity of a diagnostic test for that disease. They discuss how to calculate posttest probabilities of a disease under such uncertainty and how to calculate a distribution for a posttest probability. They show that given certain independence assumptions, uncertainty about these parameters need not complicate the calculation of patient positive predictive values: One can simply use the expected values of the parameters in the standard Bayesian formula for posttest probabilities. The discussion on how to calculate distributions for positive predictive values corrects a common and potentially important error.

A randomized trial of low-dose aspirin in the primary prevention of cardiovascular disease in women. Ridker PM, Cook NR, Lee IM, Gordon D, Gaziano JM, Manson JE, Hennekens CH, Buring JE. N Engl J Med 2005: 352(13); 1293-304. [Medline] [Abstract] [Full text] [PDF]

BACKGROUND: Randomized trials have shown that low-dose aspirin decreases the risk of a first myocardial infarction in men, with little effect on the risk of ischemic stroke. There are few similar data in women. METHODS: We randomly assigned 39,876 initially healthy women 45 years of age or older to receive 100 mg of aspirin on alternate days or placebo and then monitored them for 10 years for a first major cardiovascular event (i.e., nonfatal myocardial infarction, nonfatal stroke, or death from cardiovascular causes). RESULTS: During follow-up, 477 major cardiovascular events were confirmed in the aspirin group, as compared with 522 in the placebo group, for a nonsignificant reduction in risk with aspirin of 9 percent (relative risk, 0.91; 95 percent confidence interval, 0.80 to 1.03; P=0.13). With regard to individual end points, there was a 17 percent reduction in the risk of stroke in the aspirin group, as compared with the placebo group (relative risk, 0.83; 95 percent confidence interval, 0.69 to 0.99; P=0.04), owing to a 24 percent reduction in the risk of ischemic stroke (relative risk, 0.76; 95 percent confidence interval, 0.63 to 0.93; P=0.009) and a nonsignificant increase in the risk of hemorrhagic stroke (relative risk, 1.24; 95 percent confidence interval, 0.82 to 1.87; P=0.31). As compared with placebo, aspirin had no significant effect on the risk of fatal or nonfatal myocardial infarction (relative risk, 1.02; 95 percent confidence interval, 0.84 to 1.25; P=0.83) or death from cardiovascular causes (relative risk, 0.95; 95 percent confidence interval, 0.74 to 1.22; P=0.68). Gastrointestinal bleeding requiring transfusion was more frequent in the aspirin group than in the placebo group (relative risk, 1.40; 95 percent confidence interval, 1.07 to 1.83; P=0.02). Subgroup analyses showed that aspirin significantly reduced the risk of major cardiovascular events, ischemic stroke, and myocardial infarction among women 65 years of age or older. CONCLUSIONS: In this large, primary-prevention trial among women, aspirin lowered the risk of stroke without affecting the risk of myocardial infarction or death from cardiovascular causes, leading to a nonsignificant finding with respect to the primary end point.

Fear and loathing of pharmaceutical statistics [PDF]. Senn S. Accessed on 2005-08-16.

[My comments] Stephen Senn has often argued that the quality of industry sponsored research is higher than academic research. In this talk, he discusses some of the recent claims that commercially sponsored research is biased.

Curbing the Influence of the Drug Industry: A British View. Smith R. PLoS Med 2005: 2(9); e241. [Medline] [Full text] [PDF]

Medical journals are an extension of the marketing arm of pharmaceutical companies. Smith R. PLoS Med 2005: 2(5); e138. [Medline] [Full text] [PDF]

The Sociology of IRBís. Jaschik S, published August 15, 2005 in Inside Higher Ed. Accessed on 2005-08-16.

[Excerpt] For decades, but especially in recent years, social scientists have been frustrated by institutional review boards, campus bodies that must approve studies involving human subjects. The IRBís, as they are called, are best known for their work on informed consent with medical research. But the boards also must approve projects in which sociologists conduct surveys or do interviews ó even though such work doesnít pose any of the dangers of, say, a drug whose side effects could be deadly.

Drug researchers leak secrets to Wall St.. Timmerman L, Heath D, published August 7, 2005 in the Seattle Times. Accessed on 2005-08-16.

[Excerpt] Doctors testing new drugs are sworn to keep their research secret until drug companies announce the final results. But elite Wall Street firms ó looking to make quick profits ó have found a way to harvest these secrets: They pay doctors to divulge the details early. A Seattle Times investigation found at least 26 cases in which doctors have leaked confidential and critical details of their ongoing drug research to Wall Street firms.

Protection of Human Particpants in Survey Research: A Source Document for Institutional Review Boards. American Association for Public Opinion Research. Accessed on 2005-08-15.

[Excerpt] This statement is intended to provide information and guidance regarding survey methods and the human participant protections review process. The goal is to provide guidelines with a sound basis in the federal regulations, acknowledging the importance of protecting survey participants while maintaining the integrity of the survey research process. This information is provided with the hope that more IRBs will use this information in their review processes and to help investigators better understand how these processes apply to survey research. It is intended specifically as an aid for persons serving on or chairing IRBs. It deals with such issues as survey participation and risk, anonymity and confidentiality, benefits of surveys, and issues of informed consent. This statement is prepared as an aid to you in your deliberations about whether appropriate consideration has been given to the protection of human research participants when a study involving survey interviews or questionnaires is proposed. It is based on extensive experience with surveys by the members of our association and is intended to address a wide range of situations. Key summary points are presented below. * Participation in surveys rarely puts respondents at more than the minimal risks of everyday of life. This fact is recognized explicitly in the Federal regulations which list surveys as examples of research that can be exempted or handled with an expedited review process. * Most surveys offer benefits to advancing knowledge and to society broadly. The survey is the only method capable of providing generalizable information on a variety of aspects of the human condition. Survey data are essential to advancing our understanding of health and disease, explanations of social, psychological, and political processes, and evaluation and improvement of public policy. * Documentation of consent is often not feasible in a survey and may be potentially damaging to participation. However, in virtually all survey-based studies, the key elements of consent can be provided to respondents in a concise way at the beginning of a survey in the brief introductory statements of a telephone interview, in a cover letter for a self-administered survey or in the introductory screen in a web survey. This is true regardless of level of risk, and is consistent with the contemporary view of consent as an ongoing process rather than a document.

Ghostscript, Ghostview and GSview. Lang R. Accessed on 2005-08-12.

[Excerpt] Welcome to the Home Page for Ghostscript, an interpreter for the PostScript language and for PDF, and related software and documentation. [My comments] Many papers are published only in Postscript format (.ps) and you can use this program to view those file.

Quantum information can be negative. Oppenheim J. Accessed on 2005-08-12.

[Excerpt] Even the most ignorant cannot know less than nothing. After all, negative information makes no sense. But, although this may be true in the everyday world we are accustomed to, negative information does exist in the quantum world. Small objects such as atoms, molecules and electrons behave radically different than larger objects -- they obey the laws of quantum mechanics. What could negative information possibly mean? In short, after I send you negative information, you will know less. Such strange situations can occur because what it means to know something is very different in the quantum world. In the quantum world, we can know too much, and it is in these situations where one finds negative information. Negative information turns out to be precisely the right amount to cancel the fact that we know too much.

Creative Commons License This work is licensed under a Creative Commons Attribution 3.0 United States License. It was written by Steve Simon.

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