Voter uncertainty and failure of Duverger’s law : an empirical analysis

Abstract

Real-world simple plurality elections rarely bear out the strong Duvergerian prediction that, in equilibrium, only two competitors receive votes. Recent advances in strategic voting theory demonstrate that voter uncertainty about competitors’ true support levels in the constituency may lead to limited strategic voting, and hence incomplete desertion of trailing parties. This is the first attempt to estimate empirically the impact of uncertainty on incentives to vote strategically. Calibrating a model of strategic voting to voting results from simple plurality elections in German constituencies, it is found that strategic voters operate under high levels of uncertainty. These results support the proposition that uncertainty about party support impedes formation of Duvergerian equilibria.