I am comparing two groups with multiple measurements before and after intervention (4 measurements before and 4 measurements after intervention in both experimental and control groups).
The outcome is level of anxiety. I am planning to use generalized estimating equations to analyse the treatment effect. However, the groups are not equivalent (different hospitals) and a senior statistician colleague of mine recommended some sort of matching technique. The problem is the popular matching techniques like propensity score matching are not valid when the data are correlated and it has been also criticized. What do you suggest me of a better method of adjusting or solving this baseline differences. I would appreciate it if you give me examples with Stata commands.