382,895 papers found

This overview examines research synthesis in applied ecology and conservation. Vote counting and pooling unweighted averages are widespread despite the superiority of syntheses based on weighted combination of effects. Such analyses allow exploration of methodological uncertainty in addition to consistency of effects a…

This paper is a response to the paper "Breast Implant Illness, Outcomes with Explantation, and Potential Etiologies, a Systematic Review and Meta-Analysis". There are scientific inconsistencies and misleading statements in this paper that we felt needed to be addressed.Level of Evidence IV This journal requires th…

There exists an ever-increasing number of systematic reviews, with or without meta-analysis, in the field of nutrition. Concomitant with this increase is the increased use of such to guide future research as well as both practice and policy-based decisions. Given this increased production and consumption, a need exists…

Most meta-analyses focus on the behavior of meta-analytic means. In many cases, however, this mean is difficult to defend as a construct because the underlying distribution of studies reflects many factors, including how we as researchers choose to design studies. We present an alternative goal for meta-analysis. The a…

This article argues that while meta-analytic studies are widely used in psychological literature, heterogeneity and the potential for confounding remain major problems in the interpretation of meta-analytic study results. The article demonstrates the use of exploratory analysis including graphical methods prior to meta…

Meta-analysis is a very useful tool to combine information from different sources. Fixed effect and random effect models are widely used in meta-analysis. Despite their popularity, they may give us misleading results if the models don't fit the data but are blindly used. Therefore, like any statistical analysis, checki…

This paper investigates a likelihood-based approach in meta-analysis of clinical trials involving the baseline risk as explanatory variable. The approach takes account of the errors affecting the measure of either the treatment effect or the baseline risk, while facing the potential misspecification of the baseline ris…

A common effect size metric used to quantify the outcome of experiments for ecological meta-analysis is the response ratio (RR): the log proportional change in the means of a treatment and control group. Estimates of the variance of RR are also important for meta-analysis because they serve as weights when effect sizes…

The sentinel lymph node biopsy (SLNB) is now an accepted alternative to the axillary lymph node dissection for pathologic evaluation of the axilla in patients with early breast cancer. The use of SLNB after neoadjuvant chemotherapy (NAC) is controversial. This meta-analysis aims to determine the feasibility and the acc…

Meta-analysis is the process of combining data from multiple sources and analyzing it together to increase power and provide a clearer picture of the effect of intervention or exposure on an outcome. The process is not complicated, but requires a great deal of attention to detail. A specific set of inclusion criteria f…

We conducted a meta-analysis to examine the association between TNF 308 G/A polymorphism and risk for T1DM. Eleven reports were identified. Our study confirmed that a higher frequency of TNF 308 A allele conferred a significant risk for T1DM. Potential explanations were discussed.

Publication bias is a major and intractable problem in meta-analysis. There have been several attempts in the literature to adapt methods to allow for such bias, but these are only possible if we are prepared to make strong assumptions about the underlying selection mechanism. We discuss the assumption that the probabi…

BACKGROUND: Our objective was to systematically assess the differences in features, results, and usability of currently available meta-analysis programs. METHODS: Systematic review of software. We did an extensive search on the internet (Google, Yahoo, Altavista, and MSN) for specialized meta-analysis software. We inc…

BACKGROUND: Understanding of data-reporting methods is imperative for correct interpretation of the medical literature as well as for proper performance of future clinical research. Recent developments in biostatistics have greatly changed the types of statistical analyses used and the minimum quality standards that mu…

In a meta-analysis, the unknown parameters are often estimated using maximum likelihood, and inferences are based on asymptotic theory. It is assumed that, conditional on study characteristics included in the model, the between-study distribution and the sampling distributions of the effect sizes are normal. In practic…

Randomized clinical trials and mainly meta-analysis, have become the gold standard in the assessment of drug efficacy. A meta-analysis is a systematic review that uses statistical techniques to combine and summarize results of previous studies. Thereby, their design helps to identify and explain inconsistencies in the…

For the meta-analysis of controlled clinical trials or epidemiological studies, in which the responses are at least approximately normally distributed, a refined test for the hypothesis of no overall treatment effect is proposed. The test statistic is based on a direct estimation function for the variance of the overal…

Publication and other forms of selection biases pose a threat to the validity of meta-analysis. Funnel plots are usually used to detect such biases; asymmetrical plots are interpreted to suggest that biases are present. Using 198 published meta-analyses, we demonstrate that the shape of a funnel plot is largely determi…

In these days, more than one clinical trial is mostly performed to evaluate a new treatment or therapeutic intervention. This necessitates a combined evaluation of their results. An integration of evidence from several trials is also helpful to determine the actual knowledge. These are the main goals of meta-analyses.…

We examine two strategies for meta-analysis of a series of 2 x 2 tables with the odds ratio modelled as a linear combination of study level covariates and random effects representing between-study variation. Penalized quasi-likelihood (PQL), an approximate inference technique for generalized linear mixed models, and a…