I want to run a GLM DODS in Freesurfer to test whether patients differ from controls with regard to cortical thickness, meanwhile I want to control for several variables, both discrete as continues.
This is my manually made fsgd file
GroupDescriptorFile 1 Title fsgd pat con.txt MeasurementName Cortical Thickness
Class controls Class patients Class female Class male Class mdeft Class adni Variables Age Education Handedness
input C002 controls female mdeft 27 6 100 input C003 controls male mdeft 46 5 -89.47368622 input C004 controls female mdeft 43 4 100 input P001 patients male mdeft 32 7 -100 input P003 patients male mdeft 26 6 100 input P004 patients female mdeft 19 6 60
The problem I have is how to specify contrasts, on the Freesurfer website I found that : For DODS, the number of regressors is Nc*(Nv+1) In my case that would be 6* (3+1) = 24 Would the contrast than be:
1 -1 and 22 zero's
Does Freesurfer automatically create the correct design matrix using the fsgd file? Because it is not clear to me how I should create the design matrix with some discrete variables as confounders. Bw Petra Habets