Lars Tjelta Westlye wrote: > Hi, > > I have a couple of questions regarding mri_glmfit-sim (mc-z). > > 1. Is it correct that --sim-sign abs builds up a null distribution of max > cluster sizes regardless of the direction of the effects in the simulated > data while --sim-sign pos/neg only counts the largest positive/negative > cluster for every iteration? Or is the sign only used in the subsequent > correction procedure by mri_surfcluster and not affecting the null > distribution? > It does affect the null. > 2. Under which circumstances would it be advisable to choose --sim-sign > abs instead of pos/neg and vice versa? > When you want to do an unsigned test. It is a little odd because it can pool voxels that are both pos and neg into one cluster, but this is the same as any unsigned test (eg, F).
doug > Thanks a lot, > Lars > > _______________________________________________ > 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
