If you want to look for an interaction between your cog score and group, then use the following contrast: 0 0 0 0 0 0 1 -1 0 0 0 0 0 0 0 1 0 -1
This is an F-contrast with two rows doug On 05/29/2013 11:33 AM, Jacobs H (NP) wrote: > Hi Doug, > > Thanks for the answer. How can I examine differences between the groups? > > Best > Heidi > > ________________________________________ > Van: freesurfer-boun...@nmr.mgh.harvard.edu > [freesurfer-boun...@nmr.mgh.harvard.edu] namens Douglas N Greve > [gr...@nmr.mgh.harvard.edu] > Verzonden: woensdag 29 mei 2013 17:30 > Aan: freesurfer@nmr.mgh.harvard.edu > Onderwerp: Re: [Freesurfer] Contrast of three groups > > Hi Heidi, That will test the effect of the continuous variable averaged > over the 3 groups. > doug > > > On 05/29/2013 10:40 AM, Jacobs H (NP) wrote: >> Hi FreeSurfers, >> >> I have a more statistical question: >> >> I have three groups of subjects and I want to examine the effect of a >> continuous variable (cognition). Is it possible to examine three groups? Or >> should I do pairwise comparisons? >> What would the contrast than look like? Something like this: >> >> 0 0 0 0 0 0 0.33 0.33 0.33 >> >> (first three zeros for the three groups; three zeros for age-correction; >> three weights for cognition scores)?? >> >> Thanks! >> >> Heidi >> >> >> ================================================ >> Dr. Heidi Jacobs >> Postdoc researcher >> Faculty of Health, Medicine and Life Sciences >> School for Mental Health and Neurosciences >> Division Cognitive Neuropsychiatry and Clinical Neurosciences >> Alzheimer Center Limburg >> h.jac...@maastrichtuniversity.nl >> www.maastrichtuniversity.nl >> www.heidijacobs.nl >> >> Dr. Tanslaan 12, 6229 ET Maastricht >> P.O. Box 616, 6200 MD Maastricht, The Netherlands >> T +31 43 38 84 090 F +31 43 38 84 092 >> ================================================ >> _______________________________________________ >> 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. > > > -- 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
