In a context of shape analysis following FIRST (two sample unpaired t-test), I recently start to use randomise.
I have a concern about the threshold for the correction method stated in the subject of this mail: I chose to make t-contrast, and so I use the -S option. Anyway I have no clue (and actually I was no able to find any clue in the guide page or in the mailing list) about how chose the threshold.
As a start, I left the threshold of "3" proposed in the example I found in the FIRST user guide page (although in the example the proposed correction method is different). Anyway, while the non corrected t contrast show some significant voxel, the corrected images are always "empty". I wonder if I simply have results which do not survive a multiple comparison correction or if, as I hope, I've committed a mistake in choosing the threshold (or the multiple comparison method).
I hope someone has a hint for me