Hi,
I'm running a higher-level Flame 1 analysis using FEAT v5.98. The group-level analysis is for 30 participants, I have two EV's (Mean activation and 1 covariate of interest, covariate orthogonalised wrt mean), and I'm testing a number** of contrasts using cluster correction, z threshold 2, p threshold 0.05.
**Depending on how many contrasts I run, I get different results. For example, with two contrasts:
Mean +1 0
Covariate1 0 +1
I get significant activations for both contrasts. But, if I add further contrasts, eg:
Mean +1 0
Mean -1 0
Covariate 0 +1
Covariate 0 -1
Then my Mean contrasts result in significant activation, but neither of my covariate contrasts do.
BUT, if I open up the zstat images resulting from these two analyses in FSLVIEW, they look identical at the same given z level.
Can anyone offer advice??
Thanks,
Sarah.
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