382,895 papers found

The meta-analysis study is a type of systematic review with strong scientific rigor; it has a number of characteristics that makes it a very useful tool. However, performing and reading meta-analysis could be a challenge-the meta-analysis overcomes the limitation of small sample sizes or rare outcomes by pooling result…

Recent meta-analyses of key areas in maternity care have covered home birth and epidural analgesia. In each of these cases serious issues have arisen from the use of subjective inclusion and exclusion criteria, heterogeneity of included studies, and inclusion of studies that were conducted in settings that were not rep…

With the focus on evidence-based practice in healthcare, a well-conducted systematic review that includes a meta-analysis where indicated represents a high level of evidence for treatment effectiveness. The purpose of this commentary is to assist clinicians in understanding meta-analysis as a statistical tool using bot…

The inverse normal and Fisher's methods are two common approaches for combining P-values. Whitlock demonstrated that a weighted version of the inverse normal method, or 'weighted Z-test', is superior to Fisher's method for combining P-values for one-sided T-tests. The problem with Fisher's method is that it does not ta…

The art and science of meta-analysis, the combination of results from multiple independent studies, is now more than a century old. In the last 30 years, however, as the need for medical research and clinical practice to be based on the totality of relevant and sound evidence has been increasingly recognized, the impac…

Perhaps the greatest threat to the validity of a meta-analysis is the possibility of publication bias, where studies with interesting or statistically significant results are more likely to be published. This obviously impacts on inference concerning the treatment effect but also has implications for estimates of betwe…

Meta-analysis has several precedents; even in Confucius (VI BC) one can find a sentence about the synthesis of knowledge. Meta-analysis is a consequence of the paradigm of induction. Within this paradigm of research, meta-analysis gives an analysis of the principle of consistency of a causal association (2nd principle…

A new test for the detection of publication bias in meta-analysis with sparse binary data is proposed. The test statistic is based on observed and expected cell frequencies, and the variance of the observed cell frequencies. These quantities are utilized in a rank correlation test. Type I error rate and power of the te…

The results of a large body of candidate gene studies of behavioural and psychiatric phenotypes have been largely inconclusive, with most findings failing to replicate reliably. A variety of approaches that augment the 'traditional' candidate gene approach are discussed, including the use of meta-analysis to combine fi…

In a recent Statistics in Medicine paper, Warn, Thompson and Spiegelhalter (WTS) made a comparison between the Bayesian approach to the meta-analysis of binary outcomes and a popular Classical approach that uses summary (two-stage) techniques. They included approximate summary (two-stage) Bayesian techniques in their c…

Classical meta-analysis requires the same data from each clinical trial, thus data-reporting must be of a high-quality. Imputation methods are used to include studies that provide incomplete information on variability and the fixed and random effects of a drug. Regression models can be used to include studies other tha…

Meta-analysis is the structured and systematic integration of information from different studies of a given problem. It has been widely used to integrate findings of randomized controlled trials (RCTs) investigating the efficacy of therapeutic interventions, but its use in pathology has lagged behind its use in clinica…

Meta-analysis can be considered a multilevel statistical problem, since information within studies is combined in the presence of potential heterogeneity between studies. Here a general multilevel model framework is developed for meta-analysis to combine either summary data or individual patient outcome data from each…

When a primary study includes several indicators of the same construct, the usual strategy to meta-analytically integrate the multiple effect sizes is to average them within the study. In this paper, the numerical and conceptual differences among three procedures for averaging dependent effect sizes are shown. The proc…

The simple pooling of data is often used to provide an overall summary of subgroup data or data from a number of related studies. In simple pooling, data are combined without being weighted. Therefore, the analysis is performed as if the data were derived from a single sample. This kind of analysis ignores characterist…

This paper reviews the use of Bayesian methods in meta-analysis. Whilst there has been an explosion in the use of meta-analysis over the last few years, driven mainly by the move towards evidence-based healthcare, so too Bayesian methods are being used increasingly within medical statistics. Whilst in many meta-analysi…

A comparative review of important classic and Bayesian approaches to fixed-effects and random-effects meta-analysis of binormal ROC curves and areas underneath them is presented. The ROC analyses results of seven evaluation studies concerning the dexamethasone suppression test provide the basis for a worked example. Pa…

Exploration of the variation of treatment effect over time in randomized clinical trials with low event rates is limited by lack of power. A meta-analysis on individual patient data from such trials can partly solve the problem, but brings other computational difficulties. Using an example in hypertension, we describe…

The same proponent of meta-analysis who feels that it offers the highest level of evidence of treatment efficacy has also warned that "it is easy to do a meta-analysis; it is hard to do one well" (1). This paper has listed a series of issues that should be addressed in the construction of a good meta-analysis. A meta-a…

Use of meta-analytical (quantitative overview) techniques is now commonplace in a wide range of medical research contexts, with a rapid rise in its frequency of use being particularly apparent in the last decade. The history of meta-analyses in other fields, particularly psychology and educational research, is longer.…