Hello, FS experts:

I am now doing the group analysis with covariates(age, gender), I am using command line, not QDEC, so my Null hypothesis is:

there is no significant difference for the thickness between my two groups( 'AD' and 'CN'),  my covariates are age and gender, so if I define the classes like in the tutorial, is there an interaction between the group laber and gender, no? My question is that:

If I define the FSGD file like the example here(we have two factors, 1 variable):https://surfer.nmr.mgh.harvard.edu/fswiki/Fsgdf4G1V
surfer.nmr.mgh.harvard.edu
FSGD File (g4v1.fsgd) GroupDescriptorFile 1 Title OSGM Class MaleRight Class MaleLeft Class FemaleRight Class FemaleLeft Variables Age Input subject1 MaleRight 30 ...
Follow the tutorial, I think my contrast matrix should be like this: 
0.5 -0.5 0.5 -0.5 0 0 0 0

So I know that if you have just one factor, for example, the gender, 
we should have four columns, like:
  1. Intercept for Females
  2. Intercept for Males
  3. Slope for Females
  4. Slope for Males
But for my data, I also have the group lable(AD, CN), so anyone can explain this to me a little?

Thanks in advance!