That four group test will yield the same exact result as 1 -1 0 0
1 0 -1 0 1 0 0 -1 so I think you are ok On 02/21/2017 03:09 PM, Gold, Andrea (NIH/NIMH) [F] wrote: > > Hi, > > I am trying to run a cortical thickness analysis comparing four groups > – my goal is to conduct an omnibus F-test testing for any group > differences. I have 0 covariates/nuisance regressors. > > This would be equivalent to the “Contrast 4 group.effect.mtx” in this > page, for 3 groups: https://surfer.nmr.mgh.harvard.edu/fswiki/Fsgdf3G0V > > But, instead of 3 groups I have 4 groups. > > I thought the contrast matrix for 4 groups F-test would be: > > 1 -1 0 0 > > 0 1 -1 0 > > 0 0 1 -1 > > But for 3 groups it is: > > 1 -1 0 > > 1 0 -1 > > Would you please clarify the correct contrast matrix for this test in > Freesurfer mri_glmfit? > > > Thank you! > > Andrea > > -- > > Andrea Gold, Ph.D. > Section on Development and Affective Neuroscience > > National Institute of Mental Health > 9000 Rockville Pike MSC 2670 > Bldg. 15K > Bethesda, MD 20892 > Phone: 301-402-6955 > Fax: 301-402-2010 > > Email: andrea.g...@nih.gov > > > > _______________________________________________ > 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.
