The clinician's illusion and the psychotherapy practice: an application of stochastic modeling.

The caseload of practicing clinicians tends to be unrepresentative of the population of psychotherapy patients. This results from the fact that, although the majority of patients use relatively few treatment sessions, the majority of a clinician's time is spent with longer term cases--a minority of patients consume the majority of services. Here, a stochastic model is used to describe the development of caseloads under 4 different treatment regimens. It is shown that a psychotherapy practice will reach a steady state (a stable case mix) in relatively short time and at that this will limit the open appointment slots available each week to serve new patients. Implications for training and clinic staffing are discussed.