Structural Change in U.S. Presidents' Use of Force


  • Jong Hee Park is Assistant Professor of Political Science, The University of Chicago, 5828 S. University Avenue, Chicago, IL 60637 (

I appreciate comments from John Balz, Patrik Brandt, Sid Chib, Kevin Clarke, Michael Colaresi, Yunjong Eo, John Freeman, Kathryn Jensen, Nathan Jensen, Gyung-Ho Jeong, Luke Keele, Andrew D. Martin, James Morley, David Park, Hong Min Park, Andrew Sobel, and the participants of seminars at the 2006 American Political Science Association meeting, the 2007 Midwest Political Science Association meeting, the 2007 Summer Methods Meeting, Harvard University, University of Chicago, and University of North Carolina at Chapel Hill. I provide software to fit the Poisson changepoint model and the Poisson regression changepoint model in MCMCpack (Martin, Quinn, and Park 2008). Supplementary materials are available at the author's website:


Has there been a structural change in the way U.S. presidents use force abroad since the nineteenth century? In this article, I investigate historical changes in the use of force by U.S. presidents using Bayesian changepoint analysis. In doing so, I present an integrated Bayesian approach for analyzing changepoint problems in a Poisson regression model. To find the nature of the breaks, I estimate parameters of the Poisson regression changepoint model using Chib's (1998) hidden Markov model algorithm and Frühwirth-Schnatter and Wagner's (2006) data augmentation method. Then, I utilize transdimensional Markov chain Monte Carlo methods to detect the number of breaks. Analyzing yearly use of force data from 1890 to 1995, I find that, controlling for the effects of the Great Depression and the two world wars, the relationship between domestic conditions and the frequency of the use of force abroad fundamentally shifted in the 1940s.