Both of those contrasts will give you the same p-value. The difference is if you look at the contrast values themselves (gamma.nii). The first contrast will give you values in units of mm. The second will give you values in units of 4*mm.
doug Per Selnes wrote: > I'm trying to set ut a freesurfer group analysis. In my fsgd file there are > four groups/classes and 2 variables, like so: > > GroupDescriptorFile 1 > Title > Class Class1 > Class Class2 > Class Class3 > Class Class4 > SomeTag > > Variables Variable1 Variable2 > Input subj1 Class1 49 1 > Input subj2 Class2 50 2 > Input subj3 Class3 51 3 > Input subj3 Class4 52 4 > Input... > > I'm a bit puzzled as to how I should set up the contrasts. With DODS, there > should be a matrix of 12 regressors, and > I want to model how thickness varies with Variable2, ignoring the effects of > Variable1 and Class. Should my contrast be > > 0 0 0 0 0 0 0 0 0.25 0.25 0.25 0.25 > or > 0 0 0 0 0 0 0 0 1 1 1 1 > > or something completely different? > > I have tried both contrasts, and they yield identical (and plausible) results. > > Kind Regards, > Per Selnes > _______________________________________________ > Freesurfer mailing list > [email protected] > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer > > > -- Douglas N. Greve, Ph.D. MGH-NMR Center [email protected] 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 [email protected] 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.
