382,215 papers found

In this paper we propose a new method to analyze time-to-event data in longitudinal genetic studies. This method address the fundamental problem of incorporating uncertainty when analyzing survival data and imputed single-nucleotide polymorphisms (SNPs) from genome-wide association studies (GWAS). Our method incorporat…

Meta-analysis is increasingly used in ecology and evolutionary biology. Yet, in these fields this technique has an important limitation: phylogenetic non-independence exists among taxa, violating the statistical assumptions underlying traditional meta-analytic models. Recently, meta-analytical techniques incorporating…

This paper shows that the meta-analysis of bicycle helmet efficacy reported by Attewell, Glase, and McFadden (Accident Analysis and Prevention 2001, 345-352) was influenced by publication bias and time-trend bias that was not controlled for. As a result, the analysis reported inflated estimates of the effects of bicycl…

The DerSimonian-Laird confidence interval for the average treatment effect in meta-analysis is widely used in practice when there is heterogeneity between studies. However, it is well known that its coverage probability (the probability that the interval actually includes the true value) can be substantially below the…

Meta-analyses may contribute to more reliable knowledge about the existence of certain relations in the area of psychosomatic research. Surprisingly, the increasing popularity of meta-analysis is not reflected in the number of meta-analyses of observational studies published in Psychosomatic Medicine. This may be due t…

DNA microarray profiles are plagued by the issue of large number of variables but small number of samples and are often notorious for their low signal-to-noise ratio for clinical applications. Therefore, a great need for meta-analysis techniques is emerging to yield more valid and informative results than each experime…

The presence and impact of heterogeneity in the standard one-way random effects model in meta-analysis are often assessed using the Q statistic due to Cochran. We derive the exact distribution of this statistic under the assumptions of the random effects model, and also suggest two moment-based approximations and a sad…

Meta-analysis of receiver operating characteristic (ROC)-curve data is often done with fixed-effects models, which suffer many shortcomings. Some random-effects models have been proposed to execute a meta-analysis of ROC-curve data, but these models are not often used in practice. Straightforward modeling techniques fo…

OBJECTIVE: The study aimed to review the conclusion of a previously published meta-analysis which quantified distinct superiority of cognitive therapy to antidepressant drug-therapy (P < 0.0001). METHOD: We sought to include all studies used in the original meta-analysis. Adopting both that study's inclusion criteria…

In meta-analysis of clinical trials, often meta-regression analyses are performed to explain the heterogeneity in treatment effects that usually exist between trials. A popular explanatory variable is the risk observed in the control group, the baseline risk. The relationship between the treatment effect and the baseli…

We explored the power and consistency to detect linkage and association with meta-analysis and pooled data analysis using Genetic Analysis Workshop 14 simulated data. The first 10 replicates from Aipotu population were used. Significant linkage and association was found at all 4 regions containing the major loci for Ko…

Publication bias may exist when nonsignificant findings remain unpublished, thereby artificially inflating the apparent magnitude of an effect. This concern is not new, but it is particularly current in relation to genetic association studies. Data from a recent meta-analysis of association studies of personality were…

A number of epidemiological studies have addressed the risk of pleural mesothelioma from environmental (household and neighborhood) exposure to asbestos, but no overall risk estimate is available. We reviewed the epidemiological studies on risk of pleural mesothelioma and household or neighborhood exposure to asbestos.…

OBJECTIVE: To examine the results of meta-analyses in otolaryngology and compare these results with the individual component studies that constitute each meta-analysis. DESIGN: A retrospective review of the literature. MAIN OUTCOME MEASURES: Studies that conducted pooled statistical systematic analyses indexed on MED…

International experiences reveal the important role played by scientific research and systematic study a problems, in effectively tackling change in the health sector. Meta-analysis was introduced to address the problem of synthesizing the large quantity of information on a particular subject. It is viewed, only as a s…

Recently, 3 different meta-analytic reviews of the literature concerning the effects of extrinsic rewards on intrinsic motivation have appeared, including that by Deci, Koestner, and Ryan (1999) in this issue. Interestingly, despite their common focus, these reviews have offered dramatically opposed bottom-line conclus…

Meta-analysis has seen increasing use as a tool in epidemiology over the past five years. Although this method is relatively well accepted for use in clinical trials, its use has proved somewhat more controversial in epidemiology. If meta-analysis is viewed as an evolutionary improvement over the review article, it may…

To elucidate potential bias sources in meta-analyses, I studied whether the effect of nonsteroidal, anti-inflammatory drugs on joint count in patients with rheumatoid arthritis was related to trial design (active or placebo control), sample size, duration of treatment, drop-out rate, the existence of a wash-in period,…

The research design and methods utilized by the Collaborative Alcohol-Related Longitudinal Project are described. The project design addresses the critical need to develop procedures to assess the replicability of research results in alcohol studies. Key features of the research plan include: re-analysis of original da…

We provide a step-by-step guide on conducting a quantitative systematic review (i.e., meta-analysis) using the open-source programming language R, as well as conducting a multilevel meta-analysis, in contexts where effect sizes are non-independent (e.g., multiple studies from the same lab). Quantitative systematic revi…