Dear SPMers,
I am using some batch scripts posted to the list originally by Karl
Friston then modified by others (and me). There is a user-specified
regressor in the script an I am not quite sure what it's doing and if
I want to continue to include it. The snippet of script is this:
% design (user specified covariates)
%---------------------------------------------------------------------------
for ses=1:nses
SPM.Sess(ses).C.C = [1:208]'; % [n x c double] covariates
SPM.Sess(ses).C.name = {'Regressor (ses)'}; % [1 x c cell] names
end
Several questions:
1) Is the regressor indeed modeling linear drift? If not, what?
2) Is it redundant (colinear?) with other variables already in most
SPM models (e.g., intrinsic autocorrelations?)?
3) Can or should I try eliminating this extra regressor?
4) If yes to 2, how do I go about doing so? Simply deleting it, or
putting in [none] doesn't work.
Thanks in advance for any help...
Best wishes,
Christy
--
Christy Marshuetz
Assistant Professor
Department of Psychology
Yale University
2 Hillhouse Avenue
P.O. Box 208205
New Haven, CT 06520-8205
Phone: (203) 432-4636
|