No SDES-2015-6
Title A referendum experiment with participation quorums
Author Yoichi Hizen
Abstract This paper analyzes a yes/no referendum in which the outcome is valid only if the voter turnout is greater than a predetermined level. Such a participation quorum is argued to induce the minority group of voters to abstain strategically. Such abstention is intended to adversely affect the outcome by achieving a low voter turnout. We first construct a game-theoretic model to derive a theoretical prediction about the relationship between quorums and voting outcomes. It is shown that there exist multiple equilibria, and that strategic abstention can happen if such a participation quorum is imposed. To examine which type of outcome is more likely to be realized, we then conduct a laboratory experiment. We observe that (i) if the quorum is small, all voters go to the polls, and (ii) if the quorum is large, voters in the ex-ante majority group go to the polls, whereas voters in the ex-ante minority group tend to abstain. As a result, it is less likely that the ex-post minority group wins the referendum. However, when the quorum is large, it frequently happens that the outcome is made invalid because of low voter turnout.
Revised version published in Kyklos