title: Introduction to the special issue on the origins of modern meta-analysis.
abstract: This issue of Research Synthesis Methods is devoted to discussion of the origins of modern meta-analysis. Three articles by pioneers in development meta-analysis are by Gene Glass, Frank Schmidt, and Robert Rosenthal, respectively. They reflect on their own experiences about how they made these developments. The fourth article is by William Shadish, and seeks to analyze the impact of meta-analysis and the reasons why meta-analysis developed at the time it did, and by the people who did so. The articles are followed by commentaries by Douglas Altman, Iain Chalmers, Harris Cooper, Kay Dickersin, Larry Hedges, David Hoaglin, and Hannah Rothstein, who each comment on both the four target articles and on their own perspectives about how and why meta-analysis developed when and how it did.
authors.affiliation: University of California, Merced, Merced, CA, USA.
authors.forename: William R
authors.initials: WR
authors.lastname: Shadish
mesh_terms: D035843:Biomedical Research / Q000266:history*; D002986:Clinical Trials as Topic / Q000266:history*; D003627:Data Interpretation, Statistical; D049673:History, 20th Century; D049674:History, 21st Century; D015201:Meta-Analysis as Topic; D012107:Research Design; D012196:Review Literature as Topic
keywords: history; meta-analysis; research synthesis; systematic review