Dear Alfonso and CONN community,

Using CONN latest version, I have performed ROI connectivity analysis for 164 x 164 ROIs resting state data and classified the ROI connectivity results into two groups (e.g Group_A [1 0 1 0 .... n] and Group_B [0 1 0 1 .... n] under Setup Covariates 2nd-level tab). With aim to see group-level connectivity difference in all 164x164 ROIs and removing any age related effect, when I try to control for age in following 3 ways I read on this forum, I'm getting different results for each method;

1- Defining Age as single covariate with actual sample age values and choosing Group_A, Group_B, and Age under ROI Results Explorer tab (3 eye); for Between-subject Contrast [1 -1 0], I get the WARNING sign under Between-sources Contrast and connectivity results on attachment page 1.

2- Defining Age as separate group-level covariates with actual sample age values and zeros for non-group members and choosing Group_A, Group_B, and Age_A, Age_B under ROI Results Explorer tab (4 eye); for Between-subject Contrast [1 -1 0 0], I get the WARNING sign again under Between-sources Contrast and connectivity results on attachment page 2 (drastically different from page 1).

3- Defining Age as separate group-level covariates with centered sample age values (i.e. mean age Group_A/B minus actual sample age and zeros for non-group members) and choosing Group_A, Group_B, and Age_Centered_A, Age_Centered_B under ROI Results Explorer tab (4 eye); for Between-subject Contrast [1 -1 0 0], I get the WARNING sign again under Between-sources Contrast and connectivity results on attachment page 3 (greatly similar to page 1 but yet somewhat different at the same time).

Page 4 in attachment shows how the results look without using age as covariate. In a simple 2-sample TTEST on age vector, the age difference between two groups isn't significant (i.e p>0.05). Hence I was assuming the results would not change drastically when controlling for age. I'm of the view that all 3 methods were right and using any one would be right and should suffice. I was expecting similar results between the 3 methods, however results are quite different for each. Now I'm wondering on whats basis should I choose any one of the 3 ways above? And what the WARNING sign was about?

Can someone please shed some light on possible reason behind difference in results and WARNING sign? Thank you.

Sincerely,
Dilip