Runoff Elections in the Laboratory

• In Event: Formal Models of Domestic and International Politics

Abstract

We study experimentally the properties of the majority runoff system and compare them to the ones of plurality rule, in the setup of a divided majority. This comparison is motivated by the theoretical prediction that plurality tends to produce (weakly) higher coordination of votes on two parties than majority runoff, giving rise to Duverger's Law equilibria. The experiment shows similar levels of coordination under both mechanisms, even when sincere voting is an equilibrium under majority runoff. Behaviour seems to be explained by a limited understanding of the runoff system and by overweighting the likelihood of outright victory in the first round. We explore this hypothesis in additional treatments where the incentives to coordinate are minimized.

Authors

• Laurent Bouton, Georgetown University

• Jorge Gallego, Universidad del Rosario

• Aniol Llorente-Saguer, Max Planck Institute

• Rebecca B. Morton, New York University