Hi,
Any advice appreciated.
I have data from 4 groups of subjects (Controls and 3 Patient groups)
acquired on 3 different scanners. If possible I would like to combine
these data together but I am unsure how to model scanner as a covariate. If I
combine the Control data together then all three scanners will be represented
in this group. Would it be correct to assume that I can safely compare any
patient group with the control group and not worry about any potential effect of
scanner? What happens if I want to compare between patient groups? In this case
each Patient group has been acquired on a different scanner so I think I need to
make sure there are no main effects of scanner or scanner x group interactions? Any advice
on what a suitable design matrix and contrasts would look like would be greatly appreciated.
Cheers
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