STATISTICAL POWER ANALYSIS FOR ONE-WAY ANALYSIS OF VARIANCE - A COMPUTER-PROGRAM

To facilitate the computation of statistical power for analysis of variance, Cohen developed the index of effect size f, defined as the SD between groups divided by the SD within groups. A microcomputer program for statistical power allows the user to compute the value of f in any of several ways: by specifying the mean and SD for every cell in the ANOVA; by specifying the mean value for the two extreme cells and the pattern of dispersion for the remaining cells; by estimating the proportion of variance in the dependent variable that will be explained by group membership; and/or with reference to conventions for small, medium, and large effects. The program will compute power for any single set of parameters; it will also allow the user to generate tables and graphs showing how power will vary as a function of effect size, sample size, and α. © 1990 Psychonomic Society, Inc.