Development of a suboutcome strategy to measure interpersonal process in psychotherapy from an observer perspective.

Based on increasing recognition that the therapeutic relationship is critical in psychotherapy, the goal of this study was to establish the psychometric properties of a suboutcome strategy that could identify important in-session events involving patient-therapist interactions. Ten third-party observers were calibrated on a circumplex measure of suboutcome, a shortened version of the Wiggins' Interpersonal Adjective Scale-Revised. These observers rated four sessions from each of 28 cases of short-term psychotherapy. Each session was rated by thirds and selected to represent each quartile of a 40-session treatment protocol. The major findings indicated adequate interrater reliability and evidence for criterion validity that suggested a predictive relationship of patient and therapist affiliation to ultimate outcome, especially as observed early in treatment.