Hi again,

Another (follow-up) question about covariates. I am running ANCOVA using 3dMVM on seed-based resting state data with 3 between-subjects variables: "Group" (three groups; this is the variable of interest), "VolRemaining" (volumes remaining after scrubbing) and "Birthweight."

I'd like to incorporate both VolRemaining and Birthweight as covariates of no interest into the model. Previously when I only covaried for VolRemaining, the model was "Group*VolRemaining" but now with 2 covariates of interest I'm not sure how best to structure the model for -bsVars.

I think the 3dMVM code would look something like this:
3dMVM -prefix /PATH/TO/OUTPUT/3dMVM -jobs 5 \
-mask /PATH/TO/MASK/mask.nii.gz \
-bsVars "MODEL" \
-qVars "VolRemaining,Birthweight" \
-num_glt 6 \
-gltLabel 1 CON -gltCode 1 'Group : 1*CON' \
-gltLabel 2 POE -gltCode 2 'Group : 1*POE' \
-gltLabel 3 POME -gltCode 3 'Group : 1*POME' \
-gltLabel 4 CONvPOE -gltCode 4 'Group : 1*CON -1*POE' \
-gltLabel 5 CONvPOME -gltCode 5 'Group : 1*CON -1*POME' \
-gltLabel 6 POEvPOME -gltCode 6 'Group : 1*POE -1*POME' \
-dataTable @datatable.txt

Based on the 3dMVM help page, it seems like "Group*VolRemaining + Birthweight" or "Group + VolRemaining + Birthweight" might be appropriate for -bsVars? Is it correct to have -qVars as "VolRemaining, Birthweight" if I want to look a the main effect of Group while covarying for VolRemaining and Birthweight?

Thank you!
Janelle