Repeated measurements and test for covariance structures

[mgergreen]

I am trying to analyze my data and decide which covariance structure gives me the best AICC values. I have 9 subjects each exposed to 2 treatments, response measurements are made at 1 month, 9 month, 12 month and 15 months. I am trying to write a code to analyze this set of data using compound symmetry, unstructured and spatial power covariance structures and compare AICC values as well as overall type 3 analysis of variance.

Thank you!

[sld]

Show us the code that you've tried so far. And tell us more about your experimental protocol, especially the order in which the two treatments were assigned to each subject.