Dear SPM experts,
We used DCM to explore differences between 3 groups of patients.
I'm running DCM PEB for EEG whereby the design matrix is constructed with the first column an average and columns 2-4 specific contrasts to observe differences between the three groups. Now, we added age as a covariate in the last column to "correct" for the age of each subject.
When we add age to the design matrix, then in the PEB-review parameters screen, there are less parameters with a high Pp for the first covariate (average). However, for the age covariate we get no Pp estimated parameters.
Is it correct to assume that the average and the specific contrasts are now corrected for the age of the person? And is it normal that we do not see estimated parameters for covariate age? We were thinking that maybe estimated parameters that are influenced by age would be showed? Or does that not make any sense?
Thank you very much.
Regards,
Lisa
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