Hi All,
I'm curious if there is any way to directly specify the random slopes and intercepts covariance matrix for MIXED?
Specifically, I have a factor A with two levels, plus a pre covariate, with a post outcome. The factor A and covariate pre are clustered within another factor B, which also has two levels, and we want to treat the intercepts and sloples for the A|B and A*Pre|B as random.
Dealing with each of these separately would require a 2 x 2 diagonal covariance, and dealing with them simultaneously (if I have understood everything) is then two 2 x 2 block diagonal matrices, with a possible correlation between the 2 slopes and the two intercepts ... I don't see any obvious choice for a covariance structure from those available in SPSS v29. Have I simply missed something or how would one specify such a covariance structure?
Thanks,
Colm.
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Colm McGuinness
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