Dear FSL experts,
Consider this experiment:
A group of subjects is scanned during some kind of stimulation before
(condition A) and after (condition B) some kind of intervention.
I want to know if there is a difference in the activation caused by
the stimulation between condition A and condition B.
For fMRI data this is easily set up in a paired design using FLAME.
The next thing I want to know if a subject's age has an effect on how
much the activation changes from condition A to B.
Putting subject age into the design as a covariate would cause the
design matrix to become rank deficient and generally would not make
sense since we are looking at within-subject differences and all
subjects have the same age before and after the intervention.
How can I find out about the effect of age, or any other
subject-specific parameter such as gender or handedness, in this case?
All the best,
Anders
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