title: Researcher allegiance in psychotherapy outcome research: an overview of reviews.
abstract: Researcher allegiance (RA) is widely discussed as a risk of bias in psychotherapy outcome research. The relevance attached to RA bias is related to meta-analyses demonstrating an association of RA with treatment effects. However, recent meta-analyses have yielded mixed results. To provide more clarity on the magnitude and robustness of the RA-outcome association this article reports on a meta-meta-analysis summarizing all available meta-analytic estimates of the RA-outcome association. Random-effects methods were used. Primary study overlap was controlled. Thirty meta-analyses were included. The mean RA-outcome association was r=.262 (p=.002, I(2)=28.98%), corresponding to a moderate effect size. The RA-outcome association was robust across several moderating variables including characteristics of treatment, population, and the type of RA assessment. Allegiance towards the RA bias hypothesis moderated the RA-outcome association. The findings of this meta-meta-analysis suggest that the RA-outcome association is substantial and robust. Implications for psychotherapy outcome research are discussed.
authors.affiliation: Institute of Social and Preventive Medicine, University of Bern, Switzerland. tmunder@uni-kassel.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Munder
authors.forename: Oliver
authors.initials: O
authors.lastname: Brütsch
authors.forename: Rainer
authors.initials: R
authors.lastname: Leonhart
authors.forename: Heike
authors.initials: H
authors.lastname: Gerger
authors.forename: Jürgen
authors.initials: J
authors.lastname: Barth
mesh_terms: D015201:Meta-Analysis as Topic; D015233:Models, Statistical; D017063:Outcome Assessment, Health Care; D011613:Psychotherapy; D017594:Publication Bias; D016032:Randomized Controlled Trials as Topic / Q000941:ethics / Q000706:statistics & numerical data*; D012196:Review Literature as Topic