Hello FSLers,
I’m trying to understand some discrepancies I’ve noticed in my single subject analyses. I am attempting to generate parameter estimates (PE) for all of my subjects within an ROI.
I have a simple A r B r C r blocked design (conditions A, B, and C with interspersed rest blocks (r)). I’ve used featquery to pull the PEs for A > rest, B > rest, and C > rest contrasts.
A > rest [ 1 0 0 ]
B > rest [ 0 1 0 ]
C > rest [ 0 0 1 ]
Given that these are simple contrasts, PE should equal COPE. However, this relationship only holds for condition A. Furthermore, I have found that the PE value for condition C is consistently identical to the COPE value for condition B (for every subject, for all runs).
Clearly something is going on with my data, but I’m stumped. My design matrices look correct and I’ve double-checked the stimulus timing files that I’ve used to model each EV.
Any advice would be most appreciated!
Thanks,
Libby
|