The 40-year history of meta-analysis is traced from the vantage point of one of its originators. Research syntheses leading to the first examples of meta-analysis are identified. Early meta-analyses of the literature on psychotherapy outcomes and school class size are recounted. The influence on the development of meta-analysis of several…

Comments on the original article, "The efficacy of psychodynamic psychotherapy," by J. Shedler. Shedler declared unequivocally that "empirical evidence supports the efficacy of psychodynamic therapy" (p. 98). He did not mention any specific criticisms that have been made of evidence on psychodynamic psychotherapies or address possible distinctions…

In the past two decades, numerous meta-analyses have been published that examine the question of psychotherapy equivalence. Hunsley and Di Giulio (2002) critically reviewed this literature and concluded that there was abundant evidence that the Dodo bird verdict of equivalence across psychotherapies is false. In this article, we summarize and…

Focusing on psychotherapy research, illustrates methods for studying mediator and moderator variables in meta-analysis, discusses their advantages and disadvantages, and shows how inclusion of these variables can change interpretation of meta-analytic results. Notes that therapeutic orientation may make significant difference to outcome but only…

In this article, the authors present a multilevel (or hierarchical linear) model that illustrates issues in the application of the model to data from meta-analytic studies. In doing so, several issues are discussed that typically arise in the course of a meta-analysis. These include the presence of non-zero between-study variability, how multiple…

This article provides a critical review of the assumptions and findings of studies used to establish psychotherapies as empirically supported. The attempt to identify empirically supported therapies (ESTs) imposes particular assumptions on the use of randomized controlled trial (RCT) methodology that appear to be valid for some disorders and…

It is fitting that the concept of all having one and having prizes is attributed to the Dodo-Bird. The dodo was a flightless bird. In shape and form it was similar to the modern turkey. The dodo was native to Mauritius, where it lived for thousands of years before domestic animals brought to Mauritius hunted it to extinction. The last live…

Identifies three sources of reporting deficiency for meta-analytic results: quality (adequacy) of publicizing; quality of macrolevel reporting, and quality of microlevel reporting. Reanalysis of 25 reports from the Smith, Glass and Miller (1980) psychotherapy meta-analysis established two sources of misinformation, interrater reliabilities and…

The major youth psychotherapy meta-analyses have relied on published studies, which may have led to biased effect size estimates. To examine this possibility, the authors compared 121 dissertations with 134 published studies and found the following: (a) few differences on individual methodological variables, but, overall, stronger methodology in…

A meta-analytic study on effectiveness of behavioral and psychotherapeutic treatments for challenging behaviors in individuals with mild mental retardation is reported. Eighty articles were examined. For each comparison, several study variables and two effect sizes (percentage of nonoverlapping data--PND and percentage of zero data--PZD) were…

Evaluated the hypothesis that the apparent superiority of behavioral interventions among children is due to differences in the methodological quality of studies of behavioral and nonbehavioral treatments. Meta-analytic results found little support for this hypothesis. Because meta-analysis is a correlational technique, these results should be…