We demonstrate that all meta-analyses of partial correlations are biased, and yet hundreds of meta-analyses of partial correlation coefficients (PCCs) are conducted each year widely across economics, business, education, psychology, and medical research. To address these biases, we offer a new weighted average, UWLS[subscript +3]. UWLS[subscript…

The "LFK" index has been promoted as an improved method to detect bias in meta-analysis. Putatively, its performance does not depend on the number of studies in the meta-analysis. We conducted a simulation study, comparing the "LFK" index test to three standard tests for funnel plot asymmetry in settings with smaller or larger…

Introduction: Concerns about the risk of bias (RoB) of Meta-analysis (MAs) have grown in parallel with the exponential increase in the number of publications in science. However, this has not been properly assessed in Education. The aims were to evaluate the RoB of MAs in Education and to identify potential predictors of a lower RoB. Methods:…

Meta-analysis of diagnostic test accuracy (DTA) is a powerful statistical method for synthesizing and evaluating the diagnostic capacity of medical tests and has been extensively used by clinical physicians and healthcare decision-makers. However, publication bias (PB) threatens the validity of meta-analysis of DTA. Some statistical methods have…

The replication crisis in the social and psychological sciences is said to be due in part to publication bias and the resulting file drawer problem. Meta-analysis is often advocated as a means of resolving this crisis but is prone to the same publication bias and file drawer effects. A study of 23 meta-analyses examined the consequences of…

Content-based techniques for credibility assessment (Criteria-Based Content Analysis [CBCA], Reality Monitoring [RM]) have been shown to distinguish between experience-based and fabricated statements in previous meta-analyses. New simulations raised the question whether these results are reliable revealing that using meta-analytic methods on…

Background: Systematic reviews and meta-analyses of interventions can provide critical evidence for educators and policymakers by providing insights into the effectiveness of related interventions. The quality of included studies builds the foundation for a high-quality review, while bias in the included studies increases the risks of unreliable…

Meta-analytical methods face particular challenges in research fields such as social and political research, where studies often rest primarily on qualitative and case study research. In such contexts, where research findings are less standardized and amenable to structured synthesis, the case survey method has been proposed as a means of data…

A "P" value, or the magnitude or direction of results can influence decisions about whether, when, and how research findings are disseminated. Regardless of whether an entire study or a particular study result is unavailable because investigators considered the results to be unfavorable, bias in a meta-analysis may occur when available…

This meta-analytic review study examined the effects of out-of-school learning (OSL) activities on student attitude and motivation by combining the results of experimental studies conducted between 1990 and 2020. Out of the 1272 studies identified through the literature search, the study selected 46 studies that yielded 47 effect sizes. The effect…

The effect size of psychological counseling based on the Cognitive Behavioral Therapy (CBT) approach on depression and anxiety, was conducted using a meta-analysis method. According to the defined criteria, eight primary studies on anxiety and 21 on depression are included in the meta-analysis. The effect sizes based on a random-effects model are…

As past studies showed mixed results, this meta-analysis determined game-based learning's overall effect on students' critical thinking and tested for moderators, using 21 effect sizes from 20 empirical studies of 1,947 participants. The results showed that game-based learning had a significant positive overall effect on students' critical…

As the empirical literature in educational technology continues to grow, meta-analyses are increasingly being used to synthesise research to inform practice. However, not all meta-analyses are equal. To examine their evolution over the past 30 years, this study systematically analysed the quality of 52 meta-analyses (1988-2017) on educational…

Results of meta-analyses are potentially valuable for informing environmental policy and practice decisions. However, selective sampling of primary studies through searches exclusively using widely used bibliographic platform(s) could bias estimates of effect sizes. Such search strategies are common in environmental evidence reviews, and if risk…

Purpose: The purpose of this research note is to systematically document the extent that researchers who publish in American Speech-Language-Hearing Association (ASHA) journals search for and include unpublished literature in their meta-analyses and test for publication bias. Method: This research note searched all ASHA peer-reviewed journals for…