Hi,
We have recently figured out how to use a mask to restrict the area of the
skeleton evaluated in a DTI tbss group contrast of FA maps using
randomise. It was our hope that the lesser number of comparisons would
mean that the correction being done in the corrected p maps accurately
reflects us taking in less territory. It had been our understanding that
in a voxel-wise contrast, t values should not be affected by changing
which voxels were evaluated, only p values. However, when we used the
masks, our resulting t values were reduced overall, which leads us to
believe that voxels are not evaluated independent of one another. Is this
the case, and if so, does this mean that we cannot use a bonferroni type
of correction ourselves based on the voxels we wish to consider?
Thank you!
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