Quarterly Journal of Political Science > Vol 6 > Issue 3–4

A Regression Discontinuity Test of Strategic Voting and Duverger's Law

Thomas Fujiwara, Department of Economics, Princeton University, USA, fujiwara@princeton.edu
Suggested Citation
Thomas Fujiwara (2011), "A Regression Discontinuity Test of Strategic Voting and Duverger's Law", Quarterly Journal of Political Science: Vol. 6: No. 3–4, pp 197-233. http://dx.doi.org/10.1561/100.00010037

Publication Date: 16 Nov 2011
© 2011 T. Fujiwara
Voting theory,  Voting behavior,  Comparative politics,  Electoral institutions


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In this article:
Theoretical Framework
Empirical Strategy
Estimation Framework
Main Results
Tests for Quasi-Random Assignment
Effects in Contested and Uncontested Elections
Competing Mechanisms
Number of Candidates
Party Affiliation
Candidate Quality
Candidate Behavior and Unobserved Quality
Appendix A: Descriptive Statistics
Appendix B: Treatment Effects with Controls
Appendix C: List of Party Acronym and Names


This paper uses exogenous variation in electoral rules to test the predictions of strategic voting models and the causal validity of Duverger's Law. Exploiting a regression discontinuity design in the assignment of single-ballot and dual-ballot (runoff) plurality systems in Brazilian mayoral races, the results indicate that single-ballot plurality rule causes voters to desert third placed candidates and vote for the top two vote getters. The effects are stronger in close elections and cannot be explained by differences in the number of candidates, as well as their party affiliation and observable characteristics.