Measurement Error and Regression to the Mean in Matched Samples

This is a treatment of “regression to the mean” in matched samples produced by measurement error in matching variables. An equation expressing the respective contributions of regression and treatment effects to a difference of Y-means for two matched groups is derived, followed by an intuitive picture of regression effects showing their dependence on the variance in error and the normal distribution of error and of X. An illustration of a crude estimate of regression effects produced by measurement error in occupational prestige completes the paper.