THE EFFECT OF REGRESSION TO THE MEAN IN EPIDEMIOLOGIC AND CLINICAL STUDIES

Abstract

In this paper, we have noted the ways in which regression to the mean can affect the measurement of treatment effects in clinical and epidemiologic studies. It is apparent that regression can have a sizeable effect and may lead to erroneous conclusions concerning treatment effects. Thus, the procedures outlined here should be useful in taking regression into account at the planning stage as well as at the time of analysis.