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.