ABSTRACT
The length of the individual therapeutic session has been fixed to an hour or a fraction of it, but the length of the course of therapy has been left indefinite. A number of investigations have been addressed to this question: Is the length of therapy correlated with degree of improvement? In reviewing them certain distinctions have to be made between various kinds of temporal variables. The major study on duration was planned specifically to examine correlates of length of psychotherapy. The problem of who survives in treatment is linked with many other issues in the study of psychotherapy. The clinics in these studies selected patients who met psychological criteria for the kinds of psychotherapy offered. The interplay of clinic selection and self-selection is revealed in the Joan Williams and M. Pollack study. Williams and Pollack found no differences in demographic variables between those patients who failed to report and those who defected once treatment had started.
