eng TQMP Tutorials in Quantitative Methods for Psychology 1913-4126 2007-09-01 3 2 51 59 article Susanne Mayr susanne.mayr@uni-duesseldorf.de 1 Edgar Erdfelder erdfelder@psychologie.uni-mannheim.de 2 Axel Buchner axel.buchner@uni-duesseldorf.de 1 Franz Faul ffaul@psychologie.uni-kiel.de 3 Heinrich-Heine-Universität, Düsseldorf, Germany Universität Mannheim, Mannheim, Germany Christian-Albrechts-Universität, Kiel, Germany The purpose of this paper is to promote statistical power analysis in the behavioral sciences by introducing the easy to use GPower software. GPower is a free general power analysis program available in two essentially equivalent versions, one designed for Macintosh OS/OS X and the other for MS-DOS/Windows platforms. Psychological research examples are presented to illustrate the various features of the GPower software. In particular, a priori, post-hoc, and compromise power analyses for t-tests, F-tests, and chi-2-tests will be demonstrated. For all examples, the underlying statistical concepts as well as the implementation in GPower will be described. http://www.tqmp.org/Content/vol03-2/p051/p051.pdf Statistics statistical power