Multiple levels of analysis in psychotherapy research.

Psychotherapy research can be thought to involve multiple levels of analysis: client, therapist, and group. The authors argue that such research would benefit from the application of multilevel modeling. They illustrate the use of such a procedure for research studies of individual psychotherapy, group psychotherapy, and rolling group psychotherapy and provide SPSS syntax for all three cases. Psychotherapy is an inherently social process. Individual therapy involves a very complicated interaction between a client and therapist. Group therapy involves relationships between a therapist and each of the clients as well as relationships between clients. It is critical that the analysis of psychotherapy data explicitly recognize these interpersonal aspects of psychotherapy.