Depends on some of the details. Is spss demeaning the age? If so, are you passing qdec demeaned ages? It can also be that it shows up better in the ROI analysis (ROI analyses are often more powerful than map-based).
doug Dankner, Nathan (NIH/NIMH) [F] wrote: > Hi all, > > I've covaried age in a group difference analyses on cortical thickness data > both in qdec for vertex-based and in spss for the gyral-based data. For the > vertex-based data, covarying age has almost no effect, and if anything > intensifies the group differences. However, when run in qdec, covarying age > in this dataset wipes out almost any group differences. Is covarying in qdec > to be trusted? It seems strange to me that these two methods would result in > such extreme differences in results. Thanks, > > Nathan > > _______________________________________________ > 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
