Hi Heidi, the first contrast is correct assuming that BP is your 2nd variable. For the second design, you would make use [0 0 1 -1 0 0]. Note that you can do all of these from a single FSGD file (but using separate ones is ok too). doug
Jacobs H (NP) wrote:
Dear FreeSurfers,
I have been doing some basic cortical thickness analyses, which all went good. Now I want to analyze some additional things, and I want to make sure that my contrast files are ok. Could you help me out or give me advice?
So, I have three groups (control - MCI - Alzheimer) and I want to examine the effect of blood pressure on cortical thickness for each group separately (corrected for age centered). Thus, I would make three different fsgd files with this contrast:0 1 0
Then I want to compare how blood pressure affects the group differences in cortical thickness (controls vs MCI / MCI vs AD/ controls vs AD) when controlling for age: would that be: 0.5 -0.5 -0.5 0.5 0 0 ?
Every help is greatly appreciated!
Thank you Best 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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