Top-Two Runoff Elections (Uniquely) Dominate Plurality Rule

Abstract

Should states retain plurality rule or adopt a different voting method? We study the class of sequential plurality procedures, covering all widely-used single-winner election methods and proposals (including plurality, top-two runoffs, and instant runoff voting). We compare methods by whether a majority prefers the outcome of one method to that of another across all possible preference profiles. We show that a top-two runoff is the only procedure that robustly dominates plurality rule. All other methods perform better in some cases and worse in others. We further characterize the full set of dominance relations among sequential plurality procedures.

Keywords: Elections, Collective Decision Making, Electoral Reform, Voting Procedures

JEL Classification: D70, D72