Bandwagon effect in the pivotal voter model

Abstract

An open question in the study of electoral participation is whether the knowledge that a particular candidate is likely to win an election is advantageous or disadvantageous for such candidate. Recently, the empirical and experimental political literature has found substantial evidence of a bandwagon effect, defined as the phenomenon according to which the likely victory brings additional votes to the candidate, who ends up with a greater lead than the expected one. This result is driven, in the lab experiments, by the higher turnout among the majority supporters. Such evidence is however in stark contrast with the main theoretical model of electoral participation in public choice, the pivotal voter model, which predicts that majority supporters participate at a lower rate than minority ones. Accordingly, the previous attempts to provide a theoretical model of bandwagon relied on additional elements with respect to the pivotal voter model, such as the introduction of a psychological desire to win (Callander, 2007) or informational asymmetries on candidates' quality (Cukierman, 1991). This paper tries to reconcile this discrepancy by showing that a bandwagon effect can be generated within the pivotal voter model by concavity in the voters' utility function and thus establishes the key role of risk aversion as a determinant of bandwagon.