I have a question regarding FDR probability.
Inorder to study the FA value differences between two groups I perform
two-sample t-test under basic models in SPM2. The tmaps look good but non of
the clusters were significat at FDR/FWE < 0.05. So to reduce the multiple
comparisons,
1. I generate t map with Puncorr < 0.05 and k = 50 and save it as an image.
2. I re-do the basic model-two-sample ttest, with the t-image generated as
explicit mask.
The tmap and the t/z values are exactly the same as before and the FDR/FWE
have lower probality values, as expected. My question is;
1. using a mask as in (1) is it acceptable ? My reason for using such a mask
is that I am only interested in testing those volxels with Puncor < 0.05.
2. all clusters listed obtained with explicit mask as in (1) have same FDR
values. why is this?
Anusha
When I do two-sample t-test on noemalised FA maps between two groups
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