ABSTRACT
In this chapter you will:
Learn how to analyze data from pretest, posttest repeated-measures studies using analysis of covariance.
Learn how to do a power analysis. A power analysis helps you decide how many subjects should be included in a study. If too few subjects are included, significant effects may not be detected.
In this final chapter two important but somewhat disparate topics are discussed. The first topic is quite specific. Given what you have just learned about analyzing studies that include within-subjects factors, you might be tempted to apply such analyses to studies including pretest and posttest measures because such measures are clearly repeated. Actually, data from such studies are analyzed more easily as an analysis of covariance and an example is presented here. Some readers may be able to apply this example directly to their own work, but for all readers this final example serves as a way to summarize and exemplify the general analytic principles emphasized throughout this book.