Dear experts,
I'm analyzing diffusion metrics such as FA in the context of motor learning. I have 2 groups (Learners and controls) and scans at 3 time points during the training period. I first conducted a longitudinal analysis with 2 groups using the flexible factorial design in SPM, as per the CAT12 manual. I obtained some significant results and I would now like to investigate whether the musical and sport experience of participants has an impact on FA changes.
Can I add covariates to the same flexible factorial model where my 3 first parameters were the Scans (FA maps) of the Learners on day 1, 2 and 3, and then the 3 Scans of the control group? And then setting the contrasts to something like [-1 1 0 0 0 0 1 0], which would test whether musical experience has a positive effect on the increase in FA between day 1 and 2 in the Learners (i.e., more music experience = bigger FA increase).
Basically, my contrasts would be set up like this:
[Group1_d1 Group1_d2 Group1_d3 Group1_d1 Group1_d2 Group1_d3 Music Sport]
This seems to make sense to me but I want to ensure it is actually doing what I think it does.
Best,
Stefanie
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