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-bounces@nmr.mgh.harvard.edu [freesurfer-bounces@nmr.mgh.harvard.edu] namens Douglas N Greve [greve@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.jacobs@maastrichtuniversity.nl www.maastrichtuniversity.nl www.heidijacobs.nl
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