afni.nimh.nih.gov

The interaction effect is not really an F-test because it has only one numerator degree of freedom. So, instead of

-glfLabel 1 F-group_by-run -glfCode 1 'group : 1*group1 -1*group2 run: 1*run1 -1*run2' \

change it to a t-test:

-gltLabel 6 F-group_by-run -gltCode 6 'group : 1*group1 -1*group2 run: 1*run1 -1*run2' \

Gang