What is Effect Size Calculation in Meta-Analysis?

Effect size calculation is a fundamental aspect of meta-analysis, a statistical method that combines the results of multiple studies to draw overarching conclusions. In the context of meta-analysis, effect size quantifies the magnitude of an observed phenomenon or the strength of a relationship between variables across diverse studies. It provides a standardized metric, allowing researchers to compare and synthesize findings from different studies that may use varying measurement scales or methodologies.

There are various effect size metrics commonly employed in meta-analysis, including Cohen’s d, odds ratio, and correlation coefficients. The choice of the effect size metric depends on the nature of the data and the research question. Effect size calculation involves extracting relevant bio-statistics from individual studies, such as means, standard deviations, and sample sizes, and then applying a standardized formula to derive a common metric that reflects the strength of the observed effect.

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In meta-analysis, the aggregated effect size provides a consolidated measure of the overall impact or association under investigation. This comprehensive effect size estimate is accompanied by a confidence interval, which indicates the precision of the estimate and often serves as the basis for further statistical analyses and interpretation.

Effect size calculation in meta-analysis enhances the synthesis of diverse study results, fostering a more comprehensive understanding of the phenomena under study. It facilitates the integration of findings from disparate sources, allowing researchers to discern patterns, draw meaningful conclusions, and contribute to evidence-based decision-making in various fields.

References 

Cheung, Mike W-L. “A guide to conducting a meta-analysis with non-independent effect sizes.” Neuropsychology review 29.4 (2019): 387-396.

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