Thank you for your answer! I suspected that it could be something along those lines, but since MATLAB shares their code for built-in functions I thought that SAS might also have done so. I am not very familiar with SAS and realized that I was looking at old documentation (I think). The documentation for SAS/STAT 9.22 (link provided in the first post) gives an incorrect equation for the procedure (or it could be that the text is just misleading). The equation was changed from this complimentary distribution to the actual distribution in the documentation for SAS/STAT 13.2. See link below. http://support.sas.com/documentation/cdl/en/statug/67523/HTML/default/viewer.htm#statug_npar1way_details22.htm I have also implemented this later version of the equation and get the exact same result as SAS, indicating that this is the actual formula implemented in the SAS procedure. Once again, thank you very much for your answer. This saved me a lot of time googling for code that does not exist. ... View more