Have you looked at this page? https://surfer.nmr.mgh.harvard.edu/fswiki/FsgdExamples You should be able to generalize the two groups, one covariate, to three groups
On 08/24/2018 01:06 PM, O'Dell, Ryan wrote:
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Dear freesurfers,
I have what is likely a basic question but I'm new not only to FreeSurfer but contrast matrix design and group analysis as well, and was hoping for some help/clarification.
Basically I want to run a GLM on our structural/functional data in order to determine if there's any significant correlation between cortical thickness and cortical amyloid deposition (measured by PiB), factoring in any potential effects of APOE genotype (e3e3, e3e4, e4e4). This means I want to construct an FSGD file with a 3 groups (the 3 APOE genotypes) and 1 covariate (our calculated cortical composite PiB value) for this analysis. However, I'm struggling with the proper contrast designs which test the various hypotheses in such a setup.
Any answers, thoughts, or insights would be greatly appreciated. I know this type of analysis is also likely QDEC-able, but I think the FSGD approach would be more beneficial for my understanding of contrast matrix design. Please let me know if I've left out any information that could potentially help clarify my question/request.
Best,
Ryan O'Dell MD/PhD
PGY2 Psychiatry Resident, NRTP
Yale University
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