Published online by Cambridge University Press: 29 December 2014
Africa’s arbitrary country borders have been seized upon as sources of “natural experiments”: having randomly assigned people to different country treatments, differences in outcomes on either side of the border can then be attributed to the institutions, demographics, or policies put in place in each country. While methodologically attractive, the use of African borders as sources of natural experiments presents several potential pitfalls. We describe these pitfalls—some common to all studies that employ jurisdictional boundaries, some unique to African borders—and offer guidelines for overcoming them. We conclude that African cross-border studies can provide research advantages similar to well-executed comparative case studies, but that they frequently offer weaker inferential leverage than is claimed.
John F. McCauley, Assistant Professor of Government & Politics, Department of Government & Politics, University of Maryland, College Park, 3140 Tydings Hall, College Park MD 20742, USA (firstname.lastname@example.org). Daniel N. Posner, Professor of International Development, Department of Political Science, University of California, Los Angeles 4289 Bunche Hall, Los Angeles CA 90095, USA (email@example.com). The authors thank the UCLA Globalization Research Center Africa for financial support; Ibrahima Ouattara, Aimé Bado, Ollo Edmond Da, and Warhanti Da for their excellent research assistance, and Denis Cogneau, Elise Huillery, and the DIAL research team for sharing data. Useful comments were received from Daniel de Kadt, Chad Hazlett, members of the Working Group in African Political Economy, participants at the 2012 Princeton Experimental Research Workshop, and two anonymous reviewers.