Hello, Thanks Prof. Smith for your earlier response. I have another question about the randomise program. By default, randomise is set to do 5000 permutations. However, when I try running randomise with my model, I get a statement "4.35891e+10 required for exhaustive test." I wanted to know in such cases and in general how many permutations should be set while running the randomise program? Would 5000 permutations be enough, to make valid interpretations of the ouput? Thanks, EJ ____________________________________________________________________________________ Sick sense of humor? Visit Yahoo! TV's Comedy with an Edge to see what's on, when. http://tv.yahoo.com/collections/222