Dear freesurfers,
I'm currently making a per-vertex analysis using the --pvr
flag of mri_glmfit.
I already made within-group correlations between thickness
and lGI correcting for age and gender that worked perfectly.
However, when I tried to make a between groups
comparison, I ran into an error and I'm wondering if I did it
correctly.
I want to compare the slope of the pvr between my
groups, so I will use a DODS design.
In my fsgd file I have the following columns:
group, age, gender.
So, counting my pvr, I should have in my contrast
matrix 2*(3+1)=8 columns.
I made my contrast this way : 0 0 0 0 0 0 1 -1
However, when running mri_glmfit, I get the
following error:
ERROR: dimension mismatch between X and contrast
C22qVScon.txt X has 7 cols, C has 8 cols
As my matrix file has 6 columns corresponding to
what would be expected from my fsgd file (two for group,
gender and age, that contain the correct values), it seems
that there is only one column added for the pvr instead of
two.
Do anyone know if I made a mistake or is it not
possible to compare pvr between groups this way?
Thank you in advance for your answer,
Best regards
Elisa