Thanks for your help Ryan. I am still unable to run the model. I get the message "Custom hypothesis test X will not be preformed because the L matrix is not estimable."

Here's a statement of the problem: I have 4 treatment groups and 2 measurement points of a single dependent variable. I am trying to run a model with special contrasts so I can assess "contrast by time." All 4 groups represent treatment conditions with a combination of any set of 3 components. Here is the setup:

Cond 1) B Cond 2) AB Cond 3) ABC Cond 4) A

These are the 3 contrasts of interest: 1) Condition 3 v. 4 2) Condition 2 v. 1 3) Conditions 1, 2, and 4 v. 3

A single time point model looks like this:

GLM DV BY COND /CONTRAST (COND) SPECIAL (1 1 1 1 0 0 1 -1 1 -1 0 0 1/3 1/3 1/3 -1).

I need to use the same contrasts in a repeated measures model to assess "condition by time."

Any suggestions for how to model this?

THANKS!

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