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Dear Freesurfer experts,
I have a beginner question regarding fsgd and mtx files. For example, if I have one group and am interested in the correlation between some test score and cortical thickness/surface area, controlling for age and intracranial volume.
I would have 1 group and 3 covariates, e.g.
class 1
score age icv
subj1 1 55 20 3333
subj2 1 43 24 3333
Now if I am interested in the correlation between the test score and an anatomical parameter, I would go with the design matrix:
0 1 0 0 (doss). My question is, why does this calculate an F test, if I am only interested in one group? (I would understand a t-test with test-score slope >0, but where does the F come from?)
I am drawing a mental blank here and would appreciate your help!
Thanks a lot,
Dorothee