Coordination via Polling in Plurality Voting Games under Inertia

Abstract

We discuss a new model for strategic voting in plurality elections under uncertainty. In particular, we introduce the concept of inertia to capture players’ uncertainty about poll accuracy. We use a sequence of pre-election polls as a source of partial information. Under some behavioural assumptions, we show how this sequence can help agents to coordinate on an equilibrium outcome. We study the model analytically under some special distributions of inertia, and present some simulation results for more general distributions. Some special cases of our model yield a voting rule closely related to the Instant Runoff voting rule and give insight into the political science principle known as Duverger’s law. Our results show that the type of equilibrium and the speed of convergence to equilibrium depend strongly on the distribution of inertia and the preferences of agents.