Hello,

hope someone could help me to solve this problem for which I can't see a way out.

I want to test the effect of three different kinds of therapy on different patients:

- patients corresponds to the first level unit of analysis

- patients are nested into groups (actually, 12 different groups); so, groups are the second level of analysis

- therapy has three levels: therapy A, therapy B, therapy C

- we measure by a test the level of anxiety at four different times i.e. beginning, after 30 days, after 60 days, after 90 days.

Each participant in a group receive the same type of treatment (namely, groups 1, 2,3,4 receive therapy A, groups 5,6,7,8 receive therapy B, 9,10,11,12 receive therapy C). This is necessary because these aregroup therapies.

My interest is to test

- if groups in condition A, B, C have the same values before beginning the therapy

- how the effect of each therapy changes according to time: my hyphtoeses are that therapy A is the most effective and stable along time, therapy B is effective but only after a prolonged period of time, while therapy C is not effective.

The syntax I am writing has something uncorrect, and I think I have used the wrong approach.

Has anyone any suggestion?

Thank you in advance for any kind of help, I am really desperate.