Hi,
I’m making contrasts, and my 6 conditions are as follows:
#1 female approach
#2 male approach
#3 female withdraw
#4 male withdraw
#5 car approach
#6 car withdraw
If I want to create the contrast all-approaching-things minus fixation, I’m dealing with #1 female approach, #2 male approach, and #5 car approach. When I’m making the contrasts with mkcontrast, if I do (-a 1 -a 2 -a 5) that’s not what I want, because Matlab then weights each of them as .333. What I really want is for the car’s weight to equal the combined face’s weight to account for the 2 types of genders but only 1 type of car. Would it be correct to manually weight it as: ( .25 .25 0 0 .5 0)? I’m pretty sure that’s correct, but I just wanted to double check.
Thanks,
Stephanie
Stephanie N. DeCross
Clinical Research Coordinator
Psychiatric Neuroimaging Research Program
Martinos Center for Biomedical Imaging
Massachusetts General Hospital
149 13th Street, Charlestown, MA 02129
Phone: 617-724-3283
Fax: 617-726-4078