Hello all,
I have scanned two groups of subjects: patients and controls. For the
patient group, I have a symptom scale that I believe may be relevant, but
this scale does not apply to controls.
I would like to include this symptom scale as a covariate to remove any
contribution it makes to the group difference. Is it acceptable to create
a third EV and use demeaned numbers for the patients and zeros for
controls? It seems that approach assumes that the controls have the
patient mean.
Any thoughts would be appreciated.
Thanks,
Dost
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