Hi all,

I've read through all the archives and user guides and haven't found a direct answer to this particular question:

I'm analyzing white matter of a patient vs healthy population, looking at a behavioral continuous covariate interaction of interest. I want to control for age (as if a nuisance covariate). My assumptions are that my FEAT design model would be a blend of both the Two-Group difference adjusted for covariate and the Two groups with continuous covariate interaction as described in the GLM user guide. So EV1 and EV2 would be my two populations, EV3 and EV4 would be the all-subjects-demeaned behavioral data separated by group, and EV5 would be the all-subjects-demeaned age. Will this model correctly give me results that I can interpret as a difference between the groups' white matter in the slopes of the behavioral data, even after controlling for age? Below is an example of my design in FEAT.

EVs:

(patient)   (healthy)   (pt_bx)   (hc_bx)   (age)

EV1          EV2          EV3       EV4        EV5

1               0               .852       0            13

1               0               .359       0            16

1               0               .921       0            11

0               1               0            .933       15

0               1               0            .241       14

0               1               0            .542       18

Contrasts:

                                         EV1   EV2   EV3   EV4   EV5

C1 pt_slope > hc_slope   0        0        1        -1       0

C2 pt_slope < hc_slope   0        0        -1       1        0

Thank you for your help in advance!

Katie Bessette

Clinical Neuroscience & Development Lab

Olin Neuropsychiatry Research Center

Institute of Living / Hartford Hospital

200 Retreat Ave, Hartford, CT 06106