Supervision and Psychotherapy Process and Outcome: A Meta-analytic Review

Clinical supervision is deemed an essential element in the development of therapist competence and provision of psychotherapy to clients. However, the association between supervision and psychotherapy process and outcome has been mixed, unclear, and presumed to vary widely given the idiosyncratic features of the supervision and therapy process. Thus, to provide an up-to-date (articles published until May, 2019) quantitative summary, we conducted a meta-analytic review to examine the associations between supervision variables and psychotherapy process and outcome variables including: therapeutic relationship, client satisfaction, and treatment outcomes. Using a random effects model, the pooled Pearson's correlation between supervision and psychotherapy process and outcome variables was.21 across 12 studies (32 effects) that were included. Thus, supervision accounted for 4% of the variance in client outcomes. Approximately 54% of the total variance between studies was due to heterogeneity and not to chance. An additional meta-analysis without the 4 studies that assessed client outcomes using supervisor/therapist ratings yielded a slightly higher correlation (r = .24), accounting for 6% of the variance in client outcomes. Effect sizes regarding the therapeutic relationship and client satisfaction varied widely while effect sizes for treatment outcomes were less varied with consistently small positive effects. Supervisory working alliance was most frequently examined in assessing supervision and accounted for wider variance in effect sizes. There seemed to be less variance among specific supervision factors (e.g., style, satisfaction, structure) with consistent small to medium positive effects. Implications for future research are discussed.