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This type of review is the most commonly used of the three quantitative approaches because it can be completed relatively quickly, it is low-cost, and the data it uses (information from published, full-text articles) is relatively easy to access (Blettner et al.
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Purpose: A meta-analysis of aggregate data (AD) uses statistical analyses to generate a summary (pooled) estimate using effect estimates of individual studies reported in the published literature.
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The three primary quantitative methods of information synthesis include meta-analysis of aggregate data, meta-analysis of individual participant data (retrospective pooled studies), and prospectively planned pooled studies. Quantitative methods synthesize information across studies using statistical methods to generate summary estimates that generalize the findings of the individual studies. Qualitative reviews such as non-systematic narrative reviews and systematic reviews provide non-statistical overviews of the literature. The purpose of summarizing evidence across studies is to assess and investigate whether there is consistent or inconsistent evidence supporting specific exposure-outcome relationships and to examine sources of heterogeneity in studies that might yield differences in findings (Blettner et al. The purpose of this page is to describe and compare and contrast three quantitative approaches-meta-analyses of aggregate data, meta-analyses of individual participant data (retrospective pooled studies), and prospectively planned pooled studies-and provide resources to support the adoption of these methods.