Repeated Measures Analysis

Abstract

Repeated measures analysis is concerned with a common problem in social science research and evaluation. Often we have a situation in which we have measured the same thing at two or more points in time (called occasions), all of the measures having been taken on the same sample. Usually we assume that there are equal time periods between the occasions. For example, in the study of research teaching discussed earlier in this book we measured several outcome variables (knowledge of research, attitudes toward empirically based practice, etc.) at three points in time, the beginning of the school year, the end of the year, and again a year later. In chapter 8 we discussed the simplest kind of repeated measures analysis, one involving only two points in time and we used t tests and multivariate extensions of the t test to test for the differences in the two points in time. Now we will extend the analysis to more points in time.