[Freesurfer] Group Analysis Contrast (Follow-up)

Hi Douglas,

Thank you for your reply.

To follow up, I am setting up GLM analysis with 1 categorical variable and 1 continuous variable (age X weight). My fsgd looks like this:

*GroupDescriptorFile 1* *Title Cortical Thickness Interaction between Age and Weight* *Class class1 plus blue* *Class class2 circle green* *Variable Demean Age X Demean Weight* *Input 001 Class1 500* *Input 002 Class2 433* *...*

I want to test for an interaction between age and weight while controlling for group. Instead of putting-in age and weight separately, I multiply them to test for interaction. Can you tell me if following contrast vector will correctly test for this?

*0 0 0.5 0.5*

Thank you for your time,

-- David S. Lee Associate Research Specialist Center for Healthy Minds University of Wisconsin - Madison (608) 890-1115