ABSTRACT
Chapter 15 explains what a covariate is and provides examples of covariates. The chapter also introduces the conceptual basis for analysis of covariance and highlights key advantages of analysis of covariance compared to analysis of variance. In addition, the chapter explains how analysis of covariance can be used to account for baseline group differences in pretest-posttest study designs (e.g. randomized controlled trials). Throughout the chapter, examples are provided to demonstrate how analysis of covariance has been used to address clinical research questions. The topics discussed in this chapter expand upon those introduced in Chapters 6 and 7.
