The 3% Usage of Power Analysis

Over-reliance on significance testing has been heavily criticized in psychology. Therefore the American Psychological Association recommended supplementing the p value with additional elements such as effect sizes, confidence intervals, and considering statistical power seriously. This article elaborates the conclusions that can be drawn when these measures accompany the p value. An analysis of over 30 summary papers (including over 6,000 articles) reveals that, if at all, only effect sizes are reported in addition to p’s (38%). Only every 10th article provides a confidence interval and statistical power is reported in only 3% of articles.