Dear Freesurfur users,

I have a question about the design for a surface based analysis! I want to compare controls and patients. I have 5 covariates. One is a continous variable. The others are categorial variables (4 with 2 levels and 1 with 5 levels). I want to ajust my result with all of thoses variables. I am interested in the difference in thickness between patients and controls.
Is it possible to construct such design?
Can I put some of my variables in the "nuisance factors" ? I don't really understand the difference between "nuisance factor" and covariabes.
I really hope somebody can help me.
Thanks for all!
All the best,
Charlotte