Model-Based Cluster Analysis of Democracies

We apply model-based cluster analysis to data concerning types of democracies, creating an instrument for typologies. Noting several advantages of modelbased clustering over traditional clustering methods, we fit a normal mixture model for types of democracy in the context of the majoritarian-consensus contrast using Lijphart’s (1999) data on ten variables for 36 democracies. The model for the full period (1945-1996) finds four types of democracies: two types representing a majoritarian-consensus contrast, and two mixed ones lying between the extremes. The four-cluster solution shows that most of the countries have high cluster membership probabilities, and the solution is found to be quite stable with respect to possible measurement error in the variables included in the model. For the recent-period (1971-1996) data, most countries ∗Jaewon Jang is a Ph.D. candidate, Department of Political Science, University of South Carolina, Columbia, SC 29208 (email: [email protected]). David B. Hitchcock is an Associate Professor, Department of Statistics, University of South Carolina, Columbia, SC 29208 (email: [email protected]) (Phone: (803)777-5346. Fax: (803)777-4048). The authors thank an anonymous referee for comments and suggestions that have improved the article.