382,819 papers found

Publication bias and p-hacking are two well-known phenomena that strongly affect the scientific literature and cause severe problems in meta-analyses. Due to these phenomena, the assumptions of meta-analyses are seriously violated and the results of the studies cannot be trusted. While publication bias is very often ca…

The amount of shared data available for re-analysis has greatly increased in the last few years. Here we discuss some of the challenges raised by the analysis of these shared datasets and propose some strategies to address these issues.

Theoretically driven meta-analyses often involve testing whether study characteristics moderate an effect in a pattern that supports one of multiple competing theoretical accounts. To conduct such analyses, researchers must manually extract, i.e., code, these characteristics from sometimes hundreds of studies. Ideally,…

Modern quantitative evidence synthesis methods often combine patient-level data from different sources, known as individual participants data (IPD) sets. A specific challenge in meta-analysis of IPD sets is the presence of systematically missing data, when certain variables are not measured in some studies, and sporadi…

Meta-analysts often use standardized mean differences (SMD) to combine mean effects from studies in which the dependent variable has been measured with different instruments or scales. In this tutorial we show how the SMD is properly calculated as the difference in means divided by a between-subject reference-group, co…

Methods for random-effects meta-analysis require an estimate of the between-study variance, τ. The performance of estimators of τ(measured by bias and coverage) affects their usefulness in assessing heterogeneity of study-level effects and also the performance of related estimators of the overall effect. Ho…

Exercise stimulates a wide array of biological processes, but the mechanisms involved are incompletely understood. Many previous studies have adopted transcriptomic analyses of skeletal muscle to address particular research questions, a process that ultimately results in the collection of large amounts of publicly avai…

OBJECTIVES: The number of systematic reviews that aim to compare multiple interventions using network meta-analysis is increasing. In this study, we highlight aspects of a standard systematic review protocol that may need modification when multiple interventions are to be compared. STUDY DESIGN AND SETTING: We take th…

OBJECTIVE: Three recent meta-analyses have made the claim, albeit with some caveats, that cognitive-behavioral treatments (CBT) are superior to other psychotherapies, in general or for specific disorders (e.g., social phobia). METHOD: The purpose of the present article was to examine four issues in meta-analysis that…

The aim of this overview was to evaluate and compare the quality of systematic reviews, with or without meta-analysis, that have evaluated studies on techniques or biomaterials used for the preservation of alveolar sockets post tooth extraction in humans. An electronic search was conducted without date restrictions usi…

In a recent research article in BMC Medicine, Créquit and colleagues demonstrate how published systematic reviews in lung cancer provide a fragmented, out-of-date picture of the evidence for all treatments. The results and conclusions drawn from this study, based on cumulative network meta-analyses (NMA) of eviden…

Meta-analysis offers ecologists a powerful tool for knowledge synthesis. Albeit a form of review, it also shares many similarities with primary empirical research. Consequently, critical reading of meta-analyses incorporates criteria from both sets of approaches particularly because ecology is a discipline that embrace…