ABSTRACT
This chapter focuses on power for designs traditionally addressed using t-tests (either independent or paired). These procedures often examine treatment–control group comparisons and pre-post designs focused on two groups. The chapter presents calculations for key statistics relevant to t-test power, discussion of special considerations such as unequal sample sizes or unequal variances, and procedures for approximating statistical power. Although not recommended for conducting actual analyses, approximation techniques provide an effect tool for teaching about power. The chapter presents power analyses for independent and paired designs with R functions for primary analyses and for tests addressing violation of homogeneity of variances assumptions and unequal sample sizes.
