ABSTRACT
The previous chapters on one-way ANOVA and ANCOVA presented the extension of the independent-samples t-tests to three or more groups. In this chapter, we introduce an extension of the paired-samples t-test, which is used to compare the mean scores of the same group of participants on two occasions, to three or more occasions. This analysis is known as a repeated-measures analysis of variance (hereafter, repeated-measures ANOVA). This kind of analysis is common in pre-post studies in which researchers first give participants a pretest, then administer a treatment, and finally give participants one or more posttests (posttest/delayed posttest) to investigate the effect of the treatment on the participants (see Figure 11.1).
