I never heard anything on my post here, but it might just be high surface resolution:
http://www.mail-archive.com/neuro-mult-c...@brainvis.wustl.edu/msg00026.html On 10/16/2009 09:58 AM, Michael Harms wrote: > Your FDR analysis sounds correct. You probably have a rather small > number of "marginally" significant vertices, which is why none survive > FDR. You could try increasing the "q" value from say 0.05 to 0.1, in > which case 10% of the surviving vertices would be expected to be false > positives. > > cheers, > Mike H. > > On Fri, 2009-10-16 at 12:03 +0200, Yulia WORBE wrote: > >> Dear Freesurfer team, >> >> We are currently doing a cortical thickness studies between a group of >> psychiatric patients (n=60) and controls (n=30). We tested several >> smoothing levels (15mm, 20mm, 25mm) >> >> When setting an uncorrected threshold (such as p<0.005), we obtained >> several regions of decreased thickness, which are consistent with the >> pathology. >> >> However, when trying to correct for multiple comparisons using FDR >> ("Set Using FDR" button in qdec), the computed threshold is very high >> (e.g. 4.3 for 20mm smoothing) and, obviously, no significant regions >> are left. >> >> Did we do anything wrong in the analysis ? >> >> Thank you very much for your help, >> Yulia >> >> >> >> _______________________________________________ >> Freesurfer mailing list >> Freesurfer@nmr.mgh.harvard.edu >> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer >> > > _______________________________________________ > Freesurfer mailing list > Freesurfer@nmr.mgh.harvard.edu > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer > _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
