Hi Michael,

Yes, that was exactly my point: those pmaps with surviving voxels at P < 0.05 (FWE-corrected) only showed surviving voxels with FDR when using huge Q values (like 0.6 or so)

Thanks,

Miguel

On Wed, Dec 22, 2010 at 3:54 PM, Michael Harms <[log in to unmask]> wrote:

Hi Miguel,
I'll let someone else comment on the FDR vs. FWE issue, but a q value of
0.6 is way high.  At q=0.6, 60% of the voxels with p-values less than
the determined threshold would be expected to be false-positives voxels.
q-values of 0.05, or perhaps 0.1, are much more reasonable.

cheers,
-MH

On Wed, 2010-12-22 at 15:40 +0100, Miguel Burgaleta wrote:
>
> Hi FSLers (and more specifically T. Nichols, perhaps?),
>
>
> I am running into a strange result when using FDR to correct my
> *vox_p* output from TBSS. I get surviving voxels with FWE (P<0.05),
> but not with FDR. This happens with all of my p-maps. Does this make
> sense? I have found a couple of unanswered posts pointing in the same
> direction.
>
>
> I am feeding FDR with the same mask that I used in randomise (just in
> case it matters). Played around with the -q threshold and started
> getting non-zero answer when setting -q 0.6 or above...
>
>
> Thanks in advance for any comments,
> Miguel
>
>
>
>
>
>
>