Meta-analysis is defined as which of the following?

• A. A qualitative synthesis of a single study
• B. A descriptive summary of case reports
• C. A specific quantitative technique that amasses and summarizes the results of numerous studies using an effect size
• D. A longitudinal cohort study

Answer: (C)

Meta-analysis is a quantitative synthesis that pools results from multiple studies to estimate an overall effect. By converting each study’s findings into a common metric—an effect size such as an odds ratio, risk ratio, or standardized mean difference—results from different measures can be combined and analyzed statistically. This approach increases precision and power, helps determine whether findings are consistent across studies, and allows exploration of factors that might influence effects through methods like subgroup analyses or meta-regression. It also involves checking for heterogeneity and potential publication bias to gauge how trustworthy the overall estimate is.

This is distinct from a qualitative synthesis of a single study, a descriptive summary of case reports, or a study design that follows a single cohort over time. Those approaches do not combine quantitative results across many studies using a standardized effect size.