G*Power 3 is a major extension of, and improvement over, G*Power 2. It covers statistical power analyses for many different statistical tests of the
- F test,
- t test,
- χ2-test and
- z test families and some
- exact tests.
G*Power 3 offers five different types of statistical power analysis:
- A priori (sample size N is computed as a function of power level 1-β, significance level α, and the to-be-detected population effect size)
- Compromise (both α and 1-β are computed as functions of effect size, N, and an error probability ratio q = β/α)
- Criterion (α and the associated decision criterion are computed as a function of 1-β, the effect size, and N)
- Post-hoc (1-β is computed as a function of α, the population effect size, and N)
- Sensitivity (population effect size is computed as a function of α, 1-β, and N)
G*Power 3 provides improved effect size calculators and graphics options. It supports both a distribution-based and a design-based input mode.
G*Power 3 is available for Mac OS X 10.4 and Windows XP/Vista. G*Power 3 is free.
... 3.1.6 for Windows XP, Vista, or 7 (32 and 64 bit) (10 MB) [download]
Please make sure to choose "unpack with folders" in your unzip tool.
... 3.1.6 for Mac OS X 10.6 to 10.8 (2 MB) [download]
Mac OS X 10.4 or 10.5 users:
Please note that Apple’s new Xcode (which we used for G*Power 3.1.4 and up) only supports Mac OS X 10.6 or later. Thus, if you have Mac OS X 10.4 or 10.5, you need to use G*Power 3.1.3 (2 MB) [download].
Macintosh Power-PC users:
Please note that the development of the Power-PC version of G*Power has been discontinued. However, Power-PC users can still download G*Power 3.1.3 for Power-PC. [download PPC version]