ABSTRACT
INTRODUCTION Between-subjects analysis of variance (ANOVA) designs focus on approaches by which researchers either assign participants to or sample from independent groups. These tests often include planned or post hoc comparisons to detect differences between pairs of means or to clarify interactions. This chapter examines power for main effects, interactions, and contrasts/post hoc tests. Examples include one-and two-factor ANOVA, planned and post hoc contrasts, and simple effects tests. Additional issues include discussions of power for detecting all effects compared to power for an individual effect and artificial dichotomization.
