Ranked-choice voting and the spoiler effect

In the popular debate over the use of ranked-choice voting, it is often claimed that ranked-choice voting is less susceptible to the spoiler effect than the plurality method. We choose a definition of the term “spoiler effect” based on a survey of the popular discourse surrounding ranked-choice elections and examine whether ranked-choice voting outperforms plurality with respect to this definition. We provide analytical results under the impartial anonymous culture and impartial culture models, and simulation results using four models of voter behavior, two random and two single-peaked. We also give empirical results using a large database of American ranked-choice elections. All of our results suggest that ranked-choice voting is superior to plurality with respect to the spoiler effect.