Dear FreeSurfer Experts,
We are trying to run a between group analysis (1 patient
group 1 control group) within qdec. We are interested in investigating age-related
thickness differences between groups. Our fixed factors are ‘group’ and our continuous covariate is ‘age’. We
would like to control for other possibly confounding variables which should be
declared as “nuisance factors, is that correct?
Here is our problem. We like to put down “disease burden”
(years subject has had the disease) as our nuisance factor, since it is likely possible
that this has an effect on cortical thinning in our disease group. Yet, when we
run the model, qdec crashes. Is this because the subjects in the control group
have a “0” as disease burden?
Could you advise us on another way of controlling for
disease burden?
Cheers,
Catherine