376,100 papers found

Although dependence in effect sizes is ubiquitous, commonly used meta-analytic methods assume independent effect sizes. We describe and illustrate three-level extensions of a mixed effects meta-analytic model that accounts for various sources of dependence within and across studies, because multilevel extensions of met…

In a meta-analysis of intervention or group comparison studies, researchers often encounter the circumstance in which the standardized mean differences (d-effect sizes) are computed at multiple levels (e.g., individual vs. cluster). Cluster-level d-effect sizes may be inflated and, thus, may need to be corrected using…

Computer-assisted diagnosis (CAD) describes a diverse, heterogeneous range of applications rather than a single entity. The aims and functions of CAD systems vary considerably and comparing studies and systems is challenging due to methodological and design differences. In addition, poor study quality and reporting can…

Using microarrays, researchers are able to obtain a genome wide snapshot of a biological system under a given experimental context. Fortunately, a significant amount of gene regulation data is publicly available through various databases. We present a system that uses extra knowledge in published gene regulation relati…

A systematic literature search for evidences comparing treatment effect and harm of resurfacing versus nonresurfacing the patella in total knee arthroplasty was conducted and yielded five meta-analysis (MA), one systematic review (SR) and six randomized controlled trials not included in previous MAs/SR. The evidence su…

Meta-analysis and structural equation modeling (SEM) are two important statistical methods in the behavioral, social, and medical sciences. They are generally treated as two unrelated topics in the literature. The present article proposes a model to integrate fixed-, random-, and mixed-effects meta-analyses into the SE…

A meta-analysis of 42 clinical trials suggested that rosiglitazone, a widely used thiazolidinedione, was associated with a 43% greater risk of myocardial infarction (P = 0.03) and a 64% greater risk of cardiovascular death (P = 0.06). However, a number of criticisms have been raised that potentially undermine the concl…

In 2006, C. F. Bond Jr. and B. M. DePaulo provided a meta-analysis of means and concluded that average lie detection accuracy was significantly greater than chance for most people. Now, they have presented an analysis of standard deviations (C. F. Bond Jr. & B. M. DePaulo, 2008), claiming that there are no reliable ind…

Meta-analysis has become an important statistical tool in genetic association studies, since it may provide more powerful and precise estimates. However, meta-analytic studies are prone to several potential biases not only because the preferential publication of "positive'' studies but also due to difficulties in obtai…

Low-carbohydrate diets raise high-density lipoprotein (HDL) cholesterol levels by approximately 10%; soy protein with isoflavones raises HDL by 3% (strength of recommendation [SOR]: C, based on meta-analysis of physiologic parameters). The Dietary Approaches to Stop Hypertension (DASH) diet and multivitamin supplementa…

The following systematic reviews and meta-analyses are presented and the results discussed: the evidence-based American guidelines, five systematic reviews on naratriptan, rizatriptan, eletriptan, sumatriptan and propranolol; a meta-analysis of sumatriptan, a meta-analysis of acute migraine therapy, a meta-analysis of…

A meta-analysis of growth hormone data showing similar double amplitudes of 36 and 34% of the mean from the fit of cosine curves with periods of 1.3 and 1.0 year, respectively, suggests the desirability of analyzing available time series on variables of interest in biomedicine, to explore heretofore unknown longer-than…

Systematic reviews of original research are increasing in number. Systematic reviews are distinct from narrative reviews because they address a specific clinical question, require a comprehensive literature search, use explicit selection criteria to identify relevant studies, assess the methodologic quality of included…

It is widely assumed that body image dissatisfaction is increasing, particularly in females. We examined data from comparable samples, University of Pennsylvania introductory psychology students, over a span of about 15 years (1983-1984 versus 1995-1998). Ratings of current and ideal body figure were obtained using sil…

Numbers needed to treat (NNTs) may be used to present the effects of treatment and are the reciprocal of the absolute difference between treatment and control groups in a randomized controlled trial. NNTs are sensitive to factors that change the baseline risk of trial participants: the outcome considered; characteristi…

The random effects model is often used in meta-analyses. A corresponding significance test based on a normal approximation has been established. Its type I error is derived in this article by theoretical considerations and computer simulations. The test can be conservative as well as unacceptably anti-conservative. The…

This paper reviews recent developments in the area of computer-assisted analysis of mixture distributions (C.A.MAN). Given a biometric situation of interest in which, under homogeneity assumptions, a certain parametric density occurs, such as the Poisson, the binomial, the geometric, the normal, and so forth, then it i…

According to an unreliable meta-analysis, epoetin beta reduces the number of premature neonates needing transfusions for anaemia by 18% on average. When such children do require transfusions, two comparative trials have shown a reduction in the frequency of transfusions and total volume of blood transfused, but the cli…

The reliable detection of moderate differences in major health outcomes that arise as a result of treatment requires large-scale randomized evidence (and the appropriate interpretation of this evidence once it has been generated). This may take the form of a single mega-trial or, exceptionally, a meta-analysis of many…