Hello Freesurfer Experts,

I am trying to reproduce the values in sig.mgh using matlab, just to confirm that I know what is going on.  My numbers do not match exactly, and I am hoping someone can explain my error, or point me in the right direction.

With Qdec, I built a model with one discrete factor (A) with groups (A1) and (A2), one continuous covariate (B), and one nuisance factor (C).  I extracted the values from sig.mgh from the folder: lh-Diff-A1-A2-Cor-area-B at a specific vertex.  I also extracted the values from y.mgh at the same vertex.  I then ran an anova with contrast matrix, and expected the -log10(p-value) of the A*B term to match that of sig.mgh. 
[1 0 0;...   (A)
0 1 0;...    (B)
0 0 1;...    (C)
1 1 0];      (A*B)

Thank you for your time,
-E