Dear FSL experts and community,
I'm but a novice in FSL, and I have a dilemma as in how to define the VBM and TBSS design matrix.
My study design is randomised, placebo-controlled, crossover and counterbalanced.
Each of the 26 participants in my study underwent 4 scans: Pre-Treatment1, Post-Treatment1, Pre-Treatment2 and Post-Treatment2.
Initially, my go-to design was a 2x2 mixed effects ANOVA (2 treatments, 2 timepoints).
However, I'm not sure if this is the correct way to define the design matrix, because the 1-factor X 4 measures might be more appropriate to use, and seems simpler.
Therefore, I'd appreciate your opinion regarding the following questions:
1. Assuming a >=4 weeks washout period between treatments, and a ~2-week interval between scans in each treatment - which of the designs would be more
appropriate? (I'm also performing a paired t-test to examine carryover effects).
2. Is it necessary to define exchangeability blocks for each subject?
Thanks in advance!
Sincerely,
Yuval.
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