Hello!

My supervisor and I have a problem where we're trying to replicate some neuroimaging results by running our contrasts/analyses in the same program on two different computers at the same time. We're running our contrasts in NeuroElf. The same GLM is uploaded into both programs on each computer (the GLM has images for 41 participants; 21 in one experimental group and 20 healthy controls). The same parameters have been entered in both programs, yet when we run the contrast (OLS or robust), p < 0.005, 52 cl, one program gives us 36df and the other gives us 39df. Thus, we're getting slightly different cluster sizes and coordinates. Does anyone know why the programs differ in the degrees of freedom when everything else is entered the same?

Thank you for the help!