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African Borders as Sources of Natural Experiments Promise and Pitfalls*

  • John F. McCauley and Daniel N. Posner


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.



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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 ( Daniel N. Posner, Professor of International Development, Department of Political Science, University of California, Los Angeles 4289 Bunche Hall, Los Angeles CA 90095, USA ( 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.



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Alesina, Alberto, Easterly, William, and Matuszeski, Janina. 2011. ‘Artificial States’. Journal of the European Economic Association 9:246277.
Angrist, Joshua D., and Lavy, Victor. 1999. ‘Using Maimonides’ Rule to Estimate the Effect of Class Size on Student Achievement’. Quarterly Journal of Economics 114(2):533575.
Asiwaju, A.I. 1976. Western Yorubaland Under European Rule, 1889-1945: A Comparative Analysis of French and British Colonialism. Atlantic Highlands, NJ: Humanities Press.
Asiwaju, A.I. ed. 1985. Partitioned Africans: Ethnic Relations Across Africa’s International Boundaries, 1884-1984. London: C. Hurst & Company.
Berger, Daniel. 2009. ‘Taxes, Institutions and Local Governance: Evidence from a Natural Experiment in Colonial Nigeria’. Unpublished paper. New York: New York University.
Bloom, Howard S. 2005. ‘Randomizing Groups to Evaluate Place-Based Programs’. In Howard S. Bloom (ed.), Learning More from Social Experiments: Evolving Analytical Approaches. 115572. New York, NY: Russell Sage Foundation.
Brownlie, Ian. 1979. African Boundaries: A Legal and Diplomatic Encyclopedia. London: C. Hurst and Company.
Bubb, Ryan. 2013. ‘The Evolution of Property Rights: State Law or Informal Norms?Journal of Law and Economics 56(3):555594.
Card, David and Krueger, Alan B.. 1994. ‘Minimum Wages and Employment: A Case Study of the Fast-Food Industry in New Jersey and Pennsylvania’. American Economic Review 84(4):772793.
Coast, Ernestina. 2002. ‘Maasai Socioeconomic Conditions: A Cross-Border Comparison’. Human Ecology 30(1):79105.
Cogneau, Denis, and Moradi, Alexander Forthcoming Borders that Divide: Education and Religion in Ghana and Togo Since Colonial Times’. Journal of Economic History 74:694729.
Cogneau, Denis, Mesplé-Somps, Sandrine, and Spielvogel, Giles Forthcoming Development at the Border: Policies and National Integration in Côte d’Ivoire and its Neighbors’. World Bank Economic Review.
Druckman, James N., Green, Donald P., Kuklinski, James H., and Lupia, Arthur. 2011. ‘Experimentation in Political Science’. In James N. Druckman et al. (eds), Cambridge Handbook of Experimental Political Science. 311. New York, NY: Cambridge University Press.
Dunning, Thad. 2008. ‘Improving Causal Inference: Strengths and Limitations of Natural Experiments’. Political Research Quarterly 61:282293.
Dunning, Thad. 2012. Natural Experiments in the Social Sciences: A Design-Based Approach. New York, NY: Cambridge University Press.
Elton, Catherine. 2005. ‘The Jivaro People Between Peru and Equador’. In Paul Ganster and David Lorey (eds), Borders and Border Politics in a Globalizing World. 107115. Lanham, MD: SR Books.
Englebert, Pierre, Tarango, Stacy, and Carter, Matthew. 2002. ‘Dismemberment and Suffocation: A Contribution to the Debate on African Boundaries’. Comparative Political Studies 35:10931118.
Firmin-Sellers, Kathryn. 2000. ‘Institutions, Contexts, and Outcomes: Explaining French and British Rule in West Africa’. Comparative Politics 32(3):253272.
Gerber, Alan S., and Green, Donald P.. 2012. Field Experiments: Design, Analysis and Interpretation. New York, NY: Norton.
Gerber, Alan S., Gimpel, James G., Green, Donald P., Shaw, Daron R.. 2011. ‘How Large and Long-lasting Are the Persuasive Effects of Televised Campaign Ads? Results from a Randomized Field Experiment’. American Political Science Review 105:135150.
Green, Elliott. 2012. ‘On the Size and Shape of African States’. International Studies Quarterly 56(2):229244.
Hargreaves, J.D. 2005. ‘West African Boundary Making’. In Paul Ganster and David Lorey (eds), Borders and Border Politics in a Globalizing World. 97105. Lanham, MD: SR Books.
Huillery, Elise. 2006. ‘Colonization, Institutions and Development in the Former French West Africa’. Unpublished paper, Paris, France: DIAL-IRD.
Huillery, Elise. 2009. ‘History Matters: The Long-Term Impact of Colonial Public Investments in French West Africa’. American Economic Journal: Applied Economics 1(2):176215.
Jones, Kelly M., Pattanayak, Subhrendu, and Sills, Erin. 2006. ‘Democracy and Dictatorship: Comparing Household Innovation Across the Border of Benin and Togo’. Unpublished paper. Durham, NC: RTI and NCSU.
Krasno, Jonathan S. and Green, Donald P.. 2008. ‘Do Televised Presidential Ads Increase Voter Turnout? Evidence from a Natural Experiment’. The Journal of Politics 70:245261.
Keele, Luke, and Titiunik, Rocio. 2014a. Natural Experiments Based on Geography’. Political Science Research and Methods.
Keele, Luke, and Titiunik, Rocio. 2014b. Geographic Boundaries as Regression Discontinuities’. Political Analysis, doi:10.1093/pan/mpu014: 1-29.
Laitin, David D. 1986. Hegemony and Culture: Politics and Religious Change Among the Yoruba. Chicago, IL: The University of Chicago Press.
Lee, Alexander, and Schultz, Kenneth. 2012. ‘Comparing British and French Colonial Legacies: A Discontinuity Analysis of Cameroon’. Quarterly Journal of Political Science 7:146.
MacLean, Lauren M. 2010. Informal Institutions and Citizenship in Rural Africa: Risk and Reciprocity in Ghana and Côte d’Ivoire. New York, NY: Cambridge University Press.
McCauley, John F., and Posner, Daniel N.. 2014. ‘The Political Sources of Religious Identification: A Study on the Burkina Faso-Côte d’Ivoire Border’. Unpublished paper. Los Angeles: University of California.
Mendoza, Cristobal. 2000. ‘African Employment in Iberian Construction: A Cross-Border Analysis’. Journal of Ethnic and Migration Studies 26(4):609634.
Merolla, Jennifer, and Zechmeister, Elizabeth. 2013. ‘Evaluating Political Leaders in Times of Terror and Economic Threat: The Conditioning Influence of Politician Partisanship’. Journal of Politics 75(3):599612.
Michalopoulos, andPapaioannou, . 2011. The Long-Run Effects of the Scramble for Africa. NBER Working Paper No. 17620. National Bureau of Economic Research.
Michalopoulos, Stelios, and Papaioannou, Elias. 2014. ‘National Institutions and Subnational Development in Africa’. Quarterly Journal of Economics 129(1):151213.
Miguel, Edward. 2004. ‘Tribe or Nation? Nation Building and Public Goods in Kenya Versus Tanzania’. World Politics 56:327362.
Miles, William F.S. 1994. Hausaland Divided: Colonialism and Independence in Nigeria and Niger. Ithaca, NY: Cornell University Press.
Miles, William F.S. 2005. ‘Development, not Division: Local Versus External Perceptions of the Niger-Nigeria Border’. The Journal of Modern African Studies 43:297320.
Miles, William F.S., and Rochefort, David. 1991. ‘Nationalism Versus Ethnic Identity in Sub Saharan Africa’. American Political Science Review 85(2):393403.
Passi, Anissi. 2005. ‘Boundaries as Social Practice and Discourse: The Finnish-Russian Border’. In Paul Ganster and David Lorey (eds), Borders and Border Politics in a Globalizing World. 117136. Lanham, MD: SR Books.
Posner, Daniel N. 2004. ‘The Political Salience of Cultural Difference: Why Chewas and Tumbukas are Allies in Zambia and Adversaries in Malawi’. American Political Science Review 98(3):529545.
Ralston, Laura. 2012. ‘Less Guns, More Violence: Evidence from Disarmament in Uganda’. Unpublished paper. Boston, MA: Massachusetts Institute of Technology.
Robinson, Amanda. 2014. ‘Nationalism and Interethnic Trust: Evidence from an African Border Region’. Unpublished paper. Columbus, OH: Ohio State University.
Sahlins, Peter. 1989. Boundaries: The Making of France and Spain in the Pyrenees. Berkeley, CA: University of California Press.
Sekhon, Jasjeet S., and Titiunik, Rocio. 2012. ‘When Natural Experiments are Neither Natural Nor Experiments’. American Political Science Review 106(1):3557.
Slater, Dan, and Ziblatt, Daniel. 2013. ‘The Enduring Indispensability of the Controlled Comparison’. Comparative Political Studies 46(10):13011327.
Welch, Claude E. 1966. Dream of Unity: Pan-Africanism and Political Unification in West Africa. Ithaca, NY: Cornell University Press.

African Borders as Sources of Natural Experiments Promise and Pitfalls*

  • John F. McCauley and Daniel N. Posner


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