Post Hoc Power: A Concept Whose Time Has Come

Abstract

This article advocates the use of post hoc power analyses. First, reasons for the nonuse of a priori power analyses are presented. Next, post hoc power is defined and its utility delineated. Third, a step-by-step guide is provided for conducting post hoc power analyses. Fourth, a heuristic example is provided to illustrate how post hoc power can help to rule in/out rival explanations in the presence of statistically nonsignificant findings. Finally, several methods are outlined that describe how post hoc power analyses can be used to improve the design of independent replications.