Hi -- just following up on this message. Would "pre-threshold masking" combined with "voxel level thresholding" be similar to the small correction in SPM? My goal is to correct for the number of comparisons within a specific mask, but I don't want to do a Bonferroni since the voxels/comparisons within that mask are not all independent.
Thanks!
David
> On Sep 3, 2015, at 2:01 PM, David V. Smith <[log in to unmask]> wrote:
>
> Hi,
>
> I might be off base, but is it correct to assume that the "pre-threshold masking" + "voxel level thresholding" options in FEAT is equivalent to the small volume correction in SPM?
>
> Also, how are the "number_of_resels" computed for this approach? I'm not 100% sure where it is pulling the value it used in the -g option for ptoz in the feat logs:
>
> /usr/local/fsl/bin/fslmaths thresh_zstat4 -mas /path/to/the/prethreshold/mask.nii.gz thresh_zstat4
>
> echo 333 > thresh_zstat4.vol
> zstat4: DLH=0.81907 VOLUME=333 RESELS=5.64651
>
> /usr/local/fsl/bin/ptoz 0.05 -g 58
> 3.887894
>
> I thought the ptoz command would use the number of resels reported in the "stats/smoothness" file. Or is that the size of each resel, making the number_of_resels = VOLUME/RESELS ??
>
> Thanks!
>
> David
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