382,714 papers found

Although meta-analysis is now well established as a method of reviewing evidence, an uncritical use of the technique can be very misleading. One common problem is the failure to investigate appropriately the sources of heterogeneity, in particular the clinical differences between the studies included. This paper distin…

Multiple clinical studies require a structured synthesis of their results, especially where heterogeneous results are reported. Meta-analysis is a method that does just that. Such an epidemiological study of results across studies replaces the traditional narrative review of literature, and its study completes, but doe…

The reported studies of the association between smoking and the incidence of peptic ulcer have had nonconclusive results. Therefore, we have carried out a quantitative review including and evaluating all the factors related to that association. To this end, the techniques of meta-analysis suggested by Rosenthal have be…

The between-study variance or heterogeneity variance is an important parameter in random effects meta-analysis. This paper uses an M-estimation framework to introduce and discuss variance estimators for quantifying the uncertainty in estimates of the heterogeneity variance using the noniterative generalized method of m…

In our article (Storm, Tressoldi, & Di Risio, 2010), we claimed that the ganzfeld experimental design has proved to be consistent and reliable. However, Hyman (2010) argues that the overall evidence for psi is, in fact, contradictory and elusive. We present a case for psi research that undermines Hyman's argument. Firs…

The common formula used for converting a chi-square test into a correlation coefficient for use as an effect size in meta-analysis has a hidden assumption which may be violated in specific instances, leading to an overestimation of the effect size. A corrected formula is provided.

Quantitative literature reviews such as meta-analysis are becoming common in evolutionary biology but may be strongly affected by publication biases. Using fail-safe numbers is a quick way to estimate whether publication bias is likely to be a problem for a specific study. However, previously suggested fail-safe calcul…

Meta-analysis, the statistical combination of results from several studies to produce a single estimate of the effect of a treatment, continues to attract controversy. We illustrate the potentials and pitfalls of meta-analysis of controlled clinical trials. Cumulative meta-analysis demonstrates that this technique coul…

Wellman and colleagues' meta-analysis of performance on the false-belief task is methodologically useful, but it does not lead to any theoretical progress concerning the nature of the mechanisms that underlie the existence and development of "theory of mind." In particular, the results of this meta-analysis are perfect…

Meta-analysis continues to grow in usage despite increased concern regarding its soundness. Over twenty meta-analyses directly pertain to vaccines. Vaccine researchers need to understand the technique as well as the criticisms. Meta-analysis involves four steps. First, the meta-analyst should establish certain criteria…

Studies using doubly labeled water have identified underreporting of food intake as a problem of dietary surveys. However, reported energy intakes may be evaluated by comparison with energy requirements expressed as multiples of the basal metabolic rate, and a formula for calculating the value below which reported inta…

Conventional reviews of research on the efficacy of psychological, educational, and behavioral treatments often find considerable variation in outcome among studies and, as a consequence, fail to reach firm conclusions about the overall effectiveness of the interventions in question. In contrast meta-analytic reviews s…

Lymphangioleiomyomatosis is a rare disease which afflicts young women of childbearing age. It is sufficiently uncommon that randomization or any other systematic evaluation of regimens of treatment has been difficult. Review of scattered case reports implies that a number of hormonal manipulations may be equally effect…

The purpose of this commentary is to draw attention to some unsatisfactory features in the way that meta-analyses are presented in assisted reproduction journals. These features will be illustrated with reference to recently published papers. An appeal will be made for a more fastidious and rigorous approach to this st…

Systematic reviews of the literature, as compared with original scientific articles, are the easiest types of studies to perform, and using contemporary meta-analysis software, the press of a button yields a "pooled weighted mean" (averaging the outcomes of the included articles and adjusting for sample size). The resu…