A therapist evaluates a sample in a new treatment program after 1 month, after 2 months, and

Question:

A therapist evaluates a sample in a new treatment program after 1 month, after 2 months, and again after 3 months. Such data do not have homogeneous variance.
(a) What procedure should be used? Why?
(b) What must the therapist do to the data first?
(c) If the results are significant, what procedure should be performed?
(d) Ultimately, what will the therapist be able to identify?