Dear all,
I'm studying the relationship between grey matter volume (GMV) and questionnaire scores (Q1, Q2, Q3, Q4). I have two groups of subjects (all are healthy subjects), whose GMV differ in some regions as revealed by VBM. They also differ in Q1, Q2 and Q3. Then I extracted the mean GMV values out from these regions of all subjects. I found two sig. negative correlations between: GMV values and Q1, GMV values and Q2. However, these correlations were not found when the analysis is done on each group of subjects separately.
Is there any problem to look at the above relationship in all subjects (for the sake of power), but provided that the 2 groups of subjects have sig. group difference in GMV in these regions and Q1-3?
Thanks for your advice!
Best wishes,
Meikei
|