Abstract

This entry presents an overview of how to summarize and integrate a research literature using systematic and rigorous procedures including the statistical integration, or meta-analysis, of quantitative research results. It begins with a brief history of how research synthesis became a distinct methodology. It then sets out the seven stages of research synthesis that parallel the stages of primary research: formulating of the problem, collecting data (i.e., searching the literature); gathering and coding information from each study; evaluating the trustworthiness of the methods and results of the constituent studies; analyzing the data (if statistical integration is used, conducting the meta-analysis); interpreting the results, and preparing a document describing the synthesis. The most important aspects of each stage are described along with the problems that are most frequently encountered (e.g., censoring of data, identifying independent hypothesis tests). Next, the elements of a meta-analysis are described. These include effect size estimation and averaging, estimating the error and examining the heterogeneity in effect sizes, and the search for study-level characteristics that serve as effect size moderators. The entry concludes with brief introductions to emerging procedures for meta-analysis.