Systematic reviews and meta-analyses aggregate research findings across studies and populations, making them a valuable form of research evidence. Over the past decade, studies in medical education using these methods have increased by 630%. However, many manuscripts are not publication-ready due to inadequate planning and insufficient analyses.…

Meta-analysis is a widely used methodology to combine evidence from different sources examining a common research phenomenon, to obtain a quantitative summary of the studied phenomenon. In the medical field, multiple studies investigate the effectiveness of new treatments and meta-analysis is largely performed to generate the summary (average)…

In systematic reviews, meta-analyses are routinely applied to summarize the results of the relevant studies for a specific research question. If one can assume that in all studies the same true effect is estimated, the application of a meta-analysis with common effect (commonly referred to as fixed-effect meta-analysis) is adequate. If…

Network meta-analysis has been gaining prominence as an evidence synthesis method that enables the comprehensive synthesis and simultaneous comparison of multiple treatments. In many network meta-analyses, some of the constituent studies may have markedly different characteristics from the others, and may be influential enough to change the…

The field of evidence synthesis is growing rapidly, with a corresponding increase in the number of software tools and workflows to support the construction of systematic reviews, systematic maps, and meta-analyses. Despite much progress, however, a number of problems remain, including slow integration of new statistical or methodological…

A network meta-analysis allows a simultaneous comparison between treatments evaluated in randomised controlled trials that share at least one treatment with at least one other study. Estimates of treatment effects may be required for treatments across disconnected networks of evidence, which requires a different statistical approach and modelling…

In studies with time-to-event data, outcomes may be reported as hazard ratios (HR) or binomial counts/proportions at a specific time point. If the intent is to synthesise evidence by performing a meta-analysis or network meta-analysis (NMA) using the HR as the measure of treatment effect, studies that only report binomial data cannot be included…

In this article, we trace the development of the Campbell Collaboration and its renewed efforts to build a world library of accurate, synthesized evidence to inform policy and practice and improve human well-being worldwide. Campbell systematic reviews and related evidence synthesis products provide unbiased summaries of entire bodies of empirical…

Single-case design (SCD) research focuses on finding powerful effects, but the influence of this methodology on the evidence-based practice (EBP) movement is questionable. Meta-analytic procedures may help facilitate the role of SCD research in the EBP movement, but meta-analyses of SCDs are controversial. The current article provides an…

Evidence-based practices (EBPs) are supported as generally effective for populations of learners by bodies of high-quality and experimental research and, when aligned with stakeholder values and practical needs, should be prioritized for implementation. However, evidence-based practices are not currently available for all learner types in all…

Along with the late Howard Freeman, Richard Berk was a founding editor of "Evaluation Review" (then "Evaluation Quarterly") in 1977. He resigned as editor of this journal at the end of 2010. In this article, he reflects on his experiences. (Contains 3 notes.)

Meta-analytic methods are often used to determine the effectiveness of certain treatments across studies. However, we are often unaware of how a meta-analysis can provide value to researchers and practitioners. This paper offers a brief commentary on a meta-analysis conducted by Lin, Huang and Liou (2013) in LLT, providing further statistical…

It is well documented that studies reporting statistically significant results are more likely to be published than are studies reporting nonsignificant results--a phenomenon called "publication bias". Publication bias in meta-analytic reviews should be identified and reduced when possible. Ferguson and Brannick (2012) argued that the inclusion of…

A meta-analysis by Tran, Sanchez, Arellano, and Swanson (2011) of the published RTI literature found that the magnitude of effect size (ES) between responders and low responders at posttest was significantly moderated by the pretest ES and the type of dependent measure administered, whereas no significant moderating effects were found in the mixed…

Systematic reviews and meta-analysis are techniques for synthesizing primary empirical studies to produce a summary of effects. To facilitate this goal, the Campbell Collaboration (C2) supports reviews within the disciplines of crime and justice, education, international development, and social welfare. At the annual Campbell Colloquium, experts…