title: The effects of psychological therapies under clinically representative conditions: a meta-analysis.
abstract: Recently, concern has arisen that meta-analyses overestimate the effects of psychological therapies and that those therapies may not work under clinically representative conditions. This meta-analysis of 90 studies found that therapies are effective over a range of clinical representativeness. The projected effects of an ideal study of clinically representative therapy are similar to effect sizes in past meta-analyses. Effects increase with larger dose and when outcome measures are specific to treatment. Some clinically representative studies used self-selected treatment clients who were more distressed than available controls, and these quasi-experiments underestimated therapy effects. This study illustrates the joint use of fixed and random effects models, use of pretest effect sizes to study selection bias in quasi-experiments, and use of regression analysis to project results to an ideal study in the spirit of response surface modeling.
authors.affiliation: Department of Psychology, University of Memphis, Tennessee 38152-6400, USA. shadish@mail.psyc.memphis.edu
authors.forename: W R
authors.initials: WR
authors.lastname: Shadish
authors.forename: G E
authors.initials: GE
authors.lastname: Matt
authors.forename: A M
authors.initials: AM
authors.lastname: Navarro
authors.forename: G
authors.initials: G
authors.lastname: Phillips
mesh_terms: D006801:Humans; D001523:Mental Disorders / Q000628:therapy*; D015233:Models, Statistical; D011613:Psychotherapy / Q000379:methods*; D016032:Randomized Controlled Trials as Topic; D012044:Regression Analysis; D015983:Selection Bias; D016896:Treatment Outcome