Dear Freesurfer Experts,
1) I have 2 groups (A & B), which do not differ in terms of gender ratio. If there were no significant regions for Group-Gender interaction in mean cortical thickness in the QDEC analysis, can I conclude that gender does not influence the effect of group on thickness? The differences between A and B on mean thickness is not affected by Gender? Is this valid or do I need to add Gender as a covariate even though the group do not differ on gender ratio?
2) A reviewer pointed that it is not right to test for group differences in volume once I have tested for thickness and area, especially when there is a cluster where A and B do not differ significantly in thickness and area but they differ significantly in volume...Is this right?
Please kindly advise.
Many thanks,
Lena