Efforts to improve therapy models' general quality do not appear to have translated into improved outcomes; our results suggest that even with a therapy of perfect quality, achieved effect sizes may be modest

An Upper Limit to Youth Psychotherapy Benefit? A Meta-Analytic Copula Approach to Psychotherapy Outcomes. Payton J. Jones et al. Clinical Psychological Science, August 6, 2019. https://doi.org/10.1177/2167702619858424

Abstract: Across 50 years of research, extensive efforts have been made to improve the effectiveness of psychotherapies for children and adolescents. Yet recent evidence shows no significant improvement in youth psychotherapy outcomes. In other words, efforts to improve the general quality of therapy models do not appear to have translated directly into improved outcomes. We used multilevel meta-analytic data from 502 randomized controlled trials to generate a bivariate copula model predicting effect size as therapy quality approaches infinity. Our results suggest that even with a therapy of perfect quality, achieved effect sizes may be modest. If therapy quality and therapy outcome share a correlation of .20 (a somewhat optimistic assumption given the evidence we review), a therapy of perfect quality would produce an effect size of Hedges’s g = 0.83. We suggest that youth psychotherapy researchers complement their efforts to improve psychotherapy quality by investigating additional strategies for improving outcomes.

Keywords: meta-analysis, psychotherapy, youth psychotherapy, psychotherapy research, copula, open data, open materials