Statistical Power: How Not to Miss What’s Right in Front of You

In this chapter, we discuss the definitions of power and how to interpret power in Null Hypothesis Significance Testing. Next, the main determinants of power are outlined including the sample size, effect size (and variability), \alpha, and the type of statistical test. Each influence on power is demonstrated with example studies on statistics education and data literacy. Different types of power analyses, planning for sample sizes and sensitivity, are illustrated using power tables, popular programs, simulation, and accuracy in parameter estimation. Last, the limitations of power—especially what it does not tell you and what you should not do—are outlined to warn you about the potential misuses of power analyses. Suggestions on appropriate power planning are provided at the end of the chapter.