G*Power

G*Power 3 is a statistical power analysis program. It covers many different statistical tests of the F, t, chi-square, and z test families as well as some exact tests. G*Power 3 provides improved effect size calculators and graphics options, it supports both a distribution-based and a design-based input mode, and it offers five different types of power analyses. G*Power 3 is free.

What is new in this release:

• Renamed the Repetitions parameter in repeated measures procedures to Number of measurements (Repetitions was misleading because it incorrectly suggested that the first measurement would not be counted).
• Fixed a problem in the sensitivity analysis of the logistic regression procedure: There was an error if Odds ratio was chosen as the effect size. The problem did not occur when the effect size was specified in terms of Two probabilities.
• Mac version: The Window menu now contains the option to hide the distributions plot and the protocol section (Hide distributions & protocol menu item) so that G*Power can be accommodated to small screens. This option has been available for some time in the Windows version (see View menu).