What is a parameter?

A parameter is a number computed from a population. Contrast this with the definition of a statistic. A parameter is a constant, unchanging value. There is no random variation in a parameter. If the size of the population is large (as is typically the case), then you may find that a parameter is difficult or even impossible to compute. An example of a parameter would be:

• the average length of stay in the birth hospital for all infants born in the United States.

This work is licensed under a Creative Commons Attribution 3.0 United States License. It was written by Steve Simon on 2002-10-11, edited by Steve Simon, and was last modified on 2010-04-01. This page needs minor revisions. Category: Definitions, Category: Hypothesis testing.