Correct, you cannot do a permutation test with continuous variables (or with any non-orthogonal design matrix). If you use the --perm-force, it will do the permutation test as normal (by randomly swapping the rows), but technically the test is not legal. Having said that, I suspect that LOTS of people do exactly that. doug
On 04/04/2013 10:03 AM, Gabriel Gonzalez Escamilla wrote: > > Dear Freesurfer experts, > > > I'm having troubles when setting a permutation test, I'm making group > comparisons, but I'm introducing the Age, and cortical thickness as > niusance variables (as previously recommended). > > It seems that permutations only work for orthogonal matrices, does > this means that I cannot set any niusance variable? > > > If so, this is telling me that I can run the command with the flag > "--perm-force", and I'm wondering, which would be the implications of > force to run the permutations with niusance variables? > > > Many thanks in advance, > Gabriel > > > _______________________________________________ > 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 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.
