The way to do it is to take the maximum p-value at each voxel (this is what mri_concat does). doug
On 05/24/2013 02:10 PM, Caspar M. Schwiedrzik wrote: > Hi Doug, > I am trying to implement something like the MS/CN conjunction > suggested by Nichols. > For that, I am finding the voxels that show a significant effect at a > given threshold in both contrast maps. > I have one question about the resulting p-value. > In principle, I would tend to think that the conjunction p-value is > p-value of contrast1 x p-value of contrast 2, e.g., 0.05*0.05=0.0025. > However, one could also think that it is the max of the two p-values. > Which one is correct? > Thanks, Caspar > > > > 2013/5/23 Douglas N Greve <gr...@nmr.mgh.harvard.edu>: >> Hi Caspar, I think the 4.x should be the same as 5.x. I'm not sure about >> your fsfast question. There is nothing to automatically do it (ie, >> you'll need to run mri_concat) >> doug >> On 05/23/2013 03:06 PM, Caspar M. Schwiedrzik wrote: >>> Hi! >>> I am trying to do a conjunction analysis using mri_concat --conjunct >>> with 2 to three sig.nii as input. >>> It seems to me that the resulting map is what Nichols et al. refer to >>> as MS/GN, i.e., a test against the global null (at least one effect). >>> Is that correct, and does that depends on v4.5 / 5.x? >>> Is there something in FSFAST that would allow me to do a "real" >>> conjunction, that is, all effects significant in a given voxel? >>> Thanks, Caspar >>> _______________________________________________ >>> 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: https://gate.nmr.mgh.harvard.edu/filedrop2 >> www.nmr.mgh.harvard.edu/facility/filedrop/index.html >> Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/ >> >> _______________________________________________ >> 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. >> > -- 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: https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/facility/filedrop/index.html Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/ _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
