Sorry for not specifying. Yes, we are looking at difference in volume between the two groups using DODS. What is the most statistically sound... raw values, demeaning across the entire sample, or demeaning with groups separately? FYI, I exported the ICV values to SAS and there is a significant different between the two groups for ICV.
On Mon, Aug 29, 2016 at 2:48 PM, Douglas N Greve <gr...@nmr.mgh.harvard.edu> wrote: > not sure what you are testing, but if you are, eg, looking at the > difference between two groups regressing out ICV, then it can make a > huge difference > > > On 08/29/2016 12:36 PM, Corinna Bauer wrote: > > Hello all, > > > > I am wondering why results would change completely for between group > > volume analysis when using demeaned/mean-centered ICV compared to > > using ICV as a covariate in mri_glmfit? See the figures below. > > > > Does demeaning the covariate inherently change the results comapred to > > the raw covariate values? > > > > Thanks > > > > Corinna > > > > > > _______________________________________________ > > 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. > >
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