392,350 papers found

Systematic reviews are characterized by a methodical and replicable methodology and presentation. They involve a comprehensive search to locate all relevant published and unpublished work on a subject; a systematic integration of search results; and a critique of the extent, nature, and quality of evidence in relation…

Gastric cancer (GC) is a complex disease and a worldwide health burden due to its high prevalence and poor prognosis. A deeper knowledge of the factors involved in the development and progression of GC could help to identify subpopulations at risk that therefore require surveillance or early treatment strategies. Curre…

Writing the variance of the Mantel-Haenszel estimator under the null of homogeneity and inverting the corresponding test, we arrive at an improved confidence interval for the common risk difference in stratified 2 × 2 tables. This interval outperforms a variety of other intervals currently recommende…

BACKGROUND: Aspirin, a cyclooxygenase (COX) inhibitor with anti-inflammatory and antiplatelet properties, is widely used during pregnancy to prevent preeclampsia (PE) and intrauterine growth restriction (IUGR). Despite its benefits, low-dose aspirin (LDA) has been linked to obstetric haemorrhage, including postpartum h…

The modified method for random-effects meta-analysis, usually attributed to Hartung and Knapp and also proposed by Sidik and Jonkman, is easy to implement and is becoming advocated for general use. Here, we examine a range of potential concerns about the widespread adoption of this method. Motivated by these issues, a…

Access to big datasets from e-health records and individual participant data (IPD) meta-analysis is signalling a new advent of external validation studies for clinical prediction models. In this article, the authors illustrate novel opportunities for external validation in big, combined datasets, while drawing attentio…

Network meta-analysis is an extension of the conventional pair wise meta-analysis to include treatments that have not been compared head to head. It has in recent years caught the interest of clinical investigators in comparative effectiveness research. While allowing a simultaneous comparison of a large number of trea…

OBJECTIVE: Systematic reviewers often need to choose between two statistical methods when synthesising evidence in a meta-analysis: the fixed effect and the random effects models. The two approaches entail different assumptions about the treatment effect in the included studies. The aim of this paper was to explain the…

During the last decade a number of meta-analytic studies have been published and they triggered a debate on the true clinical usefulness of antidepressants. The current article comments on problems within the randomized controlled trials design, the study samples, the psychometric scales, the methods of meta-analysis,…

Statistical inference is problematic in the common situation in meta-analysis where the random effects model is fitted to just a handful of studies. In particular, the asymptotic theory of maximum likelihood provides a poor approximation, and Bayesian methods are sensitive to the prior specification. Hence, less effici…

In this study, we proposed to use the nonparametric bootstrap procedure to construct the confidence interval for the mean correlation r corrected for Case IV range restriction in meta-analysis (i.e., ; Hunter, Schmidt, & Le, 2006). A comprehensive Monte Carlo study was conducted to evaluate the accuracy of the parametr…

We compiled 109 species richness-altitude (SRA) relationships in arthropods to test the hypothesis that identification of shape and robustness of pattern are contingent on the selection of studies included in meta-analysis. We used attributes of their sampling design to distinguish three subsets of data according to st…

BACKGROUND: Meta-analysis methods exist for combining multiple microarray datasets. However, there are a wide range of issues associated with microarray meta-analysis and a limited ability to compare the performance of different meta-analysis methods. RESULTS: We compare eight meta-analysis methods, five existing meth…

Genetic association studies report potentially conflicting findings which meta-analysis seeks to quantify and objectively summarize. Attributing cancer to a single gene variant requires large sample sizes, which may strain resources in a primary study. Properly used, meta-analysis is a powerful tool for resolving discr…

In meta-analysis, the usual way of assessing whether a set of single studies is homogeneous is by means of the Q test. However, the Q test only informs meta-analysts about the presence versus the absence of heterogeneity, but it does not report on the extent of such heterogeneity. Recently, the I(2) index has been prop…

This article addresses the problem of heterogeneity among various studies to be combined in a meta-analysis. We adopt quasi-empirical Bayes methodology to predict the odds ratios for each study. As a result, the predicted odds ratios are pulled toward the estimated common odds ratio of the various studies under conside…

Most studies using meta-analysis try to establish relationships between traits across taxa from interspecific databases and, thus, the phylogenetic relatedness among these taxa should be taken into account to avoid pseudoreplication derived from common ancestry. This paper illustrates, with a representative example of…

The present article discusses the difficulties in using data from a meta-analysis of the effects of hormone replacement therapy on non-vertebral fractures. Comparison between the fracture data extracted from the primary studies and the data included in the meta-analysis showed discrepancies for the primary endpoint in…

OBJECTIVE: To investigate the use of the Gibbs-Sampler method in evaluating the relationship between clinic events and health risks in a meta-analysis of multiple clinical trials. METHODS: By using a generalized linear model with random-effects, Gibbs-Sampler technique was used in a meta-analysis of multiple clinical…

J. Milton and R. Wiseman (1999) attempted to replicate D. Bem and C. Honorton's (1994) meta-analysis, which yielded evidence that the ganzfeld is a suitable method for demonstrating anomalous communication. Using a database of 30 ganzfeld and autoganzfeld studies, Milton and Wiseman's meta-analysis yielded an effect si…