G*Power is a statistical power analysis program. It is a major extension of, and improvement over, the previous version, covering many different statistical tests of the F, t, chi-square, and z test families as well as some exact tests.
This software was checked for viruses and was found to be clean. Click here to see antivirus report.
As this version of the program doesn't have full support yet (i.e. the help file is not completed yet), it turned out rather difficult for me to handle.