FDR adjusts the threshold on a case-by-case basis, so it's not surprising that you see different thresholds for different data sets. The actual threshold is set based on the search space and the amount of activation. If you have a large search space, and not very much activation, then it is going to give you a high threshold. See the Genovese, Lazar, and Nichols 2002 paper for more details. Also see the Chumbley and Friston 2009 paper on the limitations of FDR.
doug Mira Michelle Raman wrote: > Hi, > I have a dataset that seems to have some very nice group differences > (please see the graph and qdec image), but they never seem to survive FDR. I > noticed when I run the "Set Using FDR", it generates a very high threshold > above 5; where as, with some of my other datasets FDR is set much lower > (often in the 2's and 3's). Can you please give me some insight into why the > threshold is being set so high? Is it solely linked to the small sample size, > or is there something additional we can do in the processing, so that regions > with such large group differences will survive correction? > > Thank you, > Mira > > > ------------------------------------------------------------------------ > > _______________________________________________ > Freesurfer mailing list > Freesurfer@nmr.mgh.harvard.edu > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer -- Douglas N. Greve, Ph.D. MGH-NMR Center gr...@nmr.mgh.harvard.edu Phone Number: 617-724-2358 Fax: 617-726-7422 Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting FileDrop: www.nmr.mgh.harvard.edu/facility/filedrop/index.html _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer The information in this e-mail is intended only for the person to whom it is addressed. If you believe this e-mail was sent to you in error and the e-mail contains patient information, please contact the Partners Compliance HelpLine at http://www.partners.org/complianceline . If the e-mail was sent to you in error but does not contain patient information, please contact the sender and properly dispose of the e-mail.
