A New Weighting Method in Meta-Analysis: The Weighting with Reliability Coefficient

This study aimed to investigate the impact of various weighting methods for effect sizes on the outcomes of meta-analyses that examined the effects of the 5E teaching method on academic achievement in science education. Two effect size weighting methods were explored: one based on the inverse of the sampling error variance and the other utilizing the reliability of measures in primary studies. The study also assessed the influence of including gray literature on the meta-analysis results, considering factors such as high heterogeneity and publication bias. The research followed a basic research design and drew data from 112 studies, encompassing a total of 149 effect sizes. An exhaustive search of databases and archives, including Google Scholar, Dergipark, HEI Thesis Center, Proquest, Science Direct, ERIC, Taylor & Francis, EBSCOhost, Web of Science, and five journals was conducted to gather these studies. Analyses were performed by utilizing the CMA v2 software and employing the random effects model. The findings demonstrated divergent outcomes between the two weighting methods—weighting by reliability coefficient yielded higher overall effect sizes and standard errors compared to weighting by inverse variance. Ultimately, the inclusion of gray literature was found to not significantly impact any of the weighting methods employed.