An alternative approach would be to use bootstrapping to determine the significance as was done by Gross et al. 2012. *Cortical signatures of cognition and their relationship to Alzheimer's disease.*
Best Regards, Donald McLaren ================= D.G. McLaren, Ph.D. Research Fellow, Department of Neurology, Massachusetts General Hospital and Harvard Medical School Postdoctoral Research Fellow, GRECC, Bedford VA Website: http://www.martinos.org/~mclaren Office: (773) 406-2464 ===================== This e-mail contains CONFIDENTIAL INFORMATION which may contain PROTECTED HEALTHCARE INFORMATION and may also be LEGALLY PRIVILEGED and which is intended only for the use of the individual or entity named above. If the reader of the e-mail is not the intended recipient or the employee or agent responsible for delivering it to the intended recipient, you are hereby notified that you are in possession of confidential and privileged information. Any unauthorized use, disclosure, copying or the taking of any action in reliance on the contents of this information is strictly prohibited and may be unlawful. If you have received this e-mail unintentionally, please immediately notify the sender via telephone at (773) 406-2464 or email. On Thu, Apr 4, 2013 at 12:16 PM, Douglas N Greve <gr...@nmr.mgh.harvard.edu>wrote: > 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. > >
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