Justin Esarey is Assistant Professor of Political Science, Rice University, PO Box 1892, Houston, TX 77251-1892, USA ([email protected]). Nathan Danneman is Data Scientist, L-3 Data Tactics, 7901 Jones Branch Dr. No. 700, McLean, VA, USA ([email protected]). This research was supported in part by a University Research Committee grant from Emory University. We thank Bill Berry, Jeff Staton, Tom Clark, Drew Linzer, Emily Ritter, John Gasper, Stu Jordan, Tim Salmon, David Siegel, Jackie DeMeritt, Deirdre McCloskey, Andrew Martin and respondents at presentations of this research at Emory University, Florida State University, Georgia State University, the University of Rochester, the 2010 Annual Meeting of the Society for Political Methodology, the 2010 Annual Meeting of the Midwest Political Science Association, and the 2009 Annual Meeting of the American Political Science Association for helpful comments and criticism. To view supplementary material for this article, please visit http://dx.doi.org/10.1017/psrm.2014.14.