Measuring Alliances: the Correlates of War Formal Interstate Alliance Dataset, 1816–2000

Abstract This article serves as a companion to the release of Version 3.0 of the Correlates of War Formal Interstate Alliance Dataset, 1816–2000. First released in 1966, the Correlates of War alliance data have greatly influenced quantitative studies of conflict, providing an important variable in the study of international conflict and cooperation. The article begins by describing the historical development and the major characteristics of the alliance dataset. The second section then discusses the procedures used to both identify and code each alliance in this revised and extended version of the data, and this is followed by a description of several important changes made to the original coding rules in order to develop this dataset, with the most notable of these changes being a more determined reliance on treaty texts rather than historical accounts for identification of alliances and alliance types. To show the effects of the revised coding decisions and the enlarged temporal domain, the final section of the article presents summary statistics for the new data and then uses the dataset to revisit two existing studies on democracy and alliance behavior. The findings indicate that jointly democratic dyads are likely to be allied only after 1945; joint democracy is negatively related to alliance formation during the 1816–1944 time period.