Download and register G*Power 3

Agreement

By downloading G*Power 3 you automatically agree to the following terms of use:

1. G*Power 3 is free for all users. Commercial distribution is strictly prohibited.
2. G*Power 3 is distributed exclusively from this website. If you wish to distribute G*Power in some other way, then you need to seek permission from the authors. Please send us an e-mail in which you specify how and for what purpose you intend to distribute G*Power .
   

If you just want to use screenshots of the G*Power interface for your publications, then you do not need to ask us for permission. However, in this case we would be grateful if you could send us a copy of your publication.

Although considerable effort has been put into program development and evaluation, there is no warranty whatsoever. Users are kindly asked to report possible bugs and difficulties in program handling by sending us an e-mail . 

Download G*Power

... 3.1.2 for Windows XP, Vista, or 7 (32 and 64 bit) (10 MB) [download] (Windows users: please make sure to choose "unpack with folders" in your unzip tool)

... 3.1.2 for Mac OS X 10.4 to 10.6 (2 MB) [download Intel version] or [download PPC version]

Please note

If you use G*Power for your research, then we would appreciate if you would include one or both of the following references (depending on what is appropriate) to the program in the papers in which you publish your results:

Faul, F., Erdfelder, E., Buchner, A., & Lang, A.-G. (2009). Statistical power analyses using G*Power 3.1: Tests for correlation and regression analyses. Behavior Research Methods, 41, 1149-1160.  

Faul, F., Erdfelder, E., Lang, A.-G., & Buchner, A. (2007). G*Power 3: A flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behavior Research Methods, 39, 175-191.   

In these papers we describe G*Power 3 and its improvements over the previous versions using a number of examples. We provide details on the algorithms that are used, and we present the relevant parameters for all tests covered by G*Power.

Register

Whenever we find a problem with G*Power we will update the program as quickly as we can.

If you want us to inform you about updates of G*Power, then we suggest that you add your e-mail address to our mailing list . This mailing list can only be used by us  and by nobody else. We will not use your e-mail address for other purposes.

Note:

Please do not be irritated when your browser tells you that it does not know the certificate of our mailing list server. You may ignore your browser's feedback in this instance.

The reason for the feedback from your browser is purely technical. Our university server uses a certificate to communicate its identity that was issued by our own authority. Your browser does not come with our authority's certificates pre-installed because the certificates were not bought from a company such as Verisign or Thawte. This would have been much too expensive for our university. If you wish, you can download and install the certificates from our university's certificate server . However, it is probably not worth the trouble if you just want to let us know your e-mail address, which is why we suggest that you simply ignore your browser's feedback in this instance.

Version History

5 January 2010 - Release 3.1.2 (Mac and Windows):

• 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).

16 December 2009 - Release 3.1 (Mac):

• Added procedures to analyze the power of tests referring to (1) single correlations based on the tetrachoric model, (2) comparisons of dependent correlations, (3) bivariate linear regression, (4) multiple linear regression based on the random predictor model, (5) logistic regression, and (6) Poisson regression.

08 December 2009 - Release 3.1.1 (Windows):

• Re-enabled options dialog for Correlation: Bivariate normal model.

29 June 2009 - Release 3.1 (Windows):

• Added procedures to analyze the power of tests referring to (1) single correlations based on the tetrachoric model, (2) comparisons of dependent correlations, (3) bivariate linear regression, (4) multiple linear regression based on the random predictor model, (5) logistic regression, and (6) Poisson regression.

24 January 2008 - Release 3.0.10 (Mac and Windows):

• Fixed a problem in the X-Y plot for a range of values for Generic F tests. The degrees of freedom were not properly set in the graph, leading to erroneous plot values.

22 January 2008 - Release 3.0.9 (Mac and Windows):

Mac:

• Eliminated the brushed metal look for better readability under Mac OS X 10.5.

Windows:

• Fixed some minor GUI problems (buttons had German titles; button in file dialog named "open" instead of "save").
• Fixed problems with distribution plots (plots were sometimes not appropriately clipped when copied or saved as metafile; drawing glitches with some very steep curves).
• The file dialog shown when saving graphs or protocols now uses the user's home directory (myDocuments) as defaults directory.
  

10 October 2007 - Release 3.0.8 (Mac and Windows):

Mac and Windows:

• Fixed a serious bug in the CDF routine of the noncentral t-distribution introduced in the bugfix release 3.0.7. Please update immediately if you installed version 3.0.7.

8 October 2007 - Release 3.0.7 (Mac and Windows):

Mac and Windows:

• Fixed a bug in the function calculating the CDF of the noncentral t-distribution that occasionally led  to (obviously) wrong values when p was very close to 1. All power routines based on the t-distribution were affected by this bug.

14 August 2007 - Release 3.0.6 (Mac only):
Mac: 

• Fixed a bug in the routine that draws the central and noncentral t distributions for two-tailed tests. When alpha was very small, this bug could cause G*Power to crash.

03 July 2007 - Release 3.0.5 (Mac and Windows):
Mac and Windows: 

• Fixed a bug in the Power Plot (opened using the X-Y-plot for a range of values button) for F-Test: MANOVA: Global effects and F-Test: MANOVA: Special effects and interactions. Sometimes some of the variables were not correctly set in the plot procedure which led to erroneous values in the graphs and the associated tables.

26 June 2007 - Release 3.0.4 (Mac and Windows):

Mac and Windows: 

• Fixed a bug in the Power Plot (opened using the X-Y-plot for a range of values button) for F-Test: Multiple Regression: Special (R2 increase). The numerator df value was not always correctly determined in the plot procedure which led to erroneous values in the graphs and the associated tables. 
• Fixed some minor problems with t tests. G•Power now checkes for invalid null effect sizes in a priori analyses. The t distribution PDF routine is now more robust for very large degrees of freedom by explicitly using a normal approximation in these cases. 
• When the Power Plot window was first opened by pressing the  X-Y plot for a range of values button, the default was to show 4 plots simultaneously. The default has been changed to 1 plot. 
• Corrected some parsing errors in the calculator (in the Mac version, this only concerns text input in normal input fields). 
• Corrected a label in the effect size drawer for ANOVA: Fixed effects, omnibus, one-way. In the From variance input mode, the Variance within group field was erroneously labeled Error variance.

Windows only

• Fixed a problem with moving the main window when the effect size drawer is open. Sometimes the mouse pointer appeared to be "glued" to the window and the movement could not be stopped properly.

1 March 2007 - Release 3.0.3 (Mac and Windows):

Mac and Windows:

• Fixed a bug in the XY-plots for a range of values for F-Test: ANOVA: Fixed effects, special, main effects and interactions. The df1 value was not always correctly determined in the plot procedure which led to erroneous values in the plots.
• Fixed the problem in the plot procedure that (due to rounding errors) the last point on the x-axis was sometimes not included in the plot.

28 February 2007 - Release 3.0.2 (Mac and Windows):

Mac and Windows:

• Fixed a probem with tooltips for effect size conventions which were not always shown.

Windows only:

• Added options mainly intended to make G*Power usable with low resolution displays (800 x 600 pixels)

• The distribution/protocol view and the test/analysis selection view in the main window can be hidden temporarily to save space. To hide/show these sub-views press F4 (plot/protocol) and F5 (test/analysis), respectively, while the main window is active. There are also corresponding entries in the View menu.

• The Graph window can now be made resizable. To do this choose "Resizable Window" in the View menu of the Graph window. Besides enabling (restricted) resizability this option initially shrinks the window to a size that fits into a 800 x 600 screen. Deselecting the option restores the Graph window to the fixed size for which G*Power was optimized.    

Mac only:

• Fixed a cosmetic problem when drawing "extreme" central and non-central distributions.

15 January 2007 - Release 3.0.1 (Windows):

• Effect size calculation for t-test, difference between two indepent means (two groups), case n1 = n2: The wrong means---those of case n1 ≠ n2---were used to calcultate the effect size. This problem has been fixed.
  
• Minor cosmetic changes.
• New Readme file.
• Updated installation instruction.

12.01.2007 - First release of version 3.0.0  (Mac OS X 10.4/ Windows XP/Vista)