A Referendum Experiment with Participation Quorums

This paper conducts a laboratory experiment focused on ayes/noreferendum in which the outcome is valid only if voter turnout is greater than a predetermined level. Such a participation quorum is argued to induce the minority group of voters to abstain strategically in particular when the quorum is large. In our experiment, subjects are randomly divided into two groupsyesandnoin advance of voting, and the level of quorum changes round by round. We observe that (i) if the quorum is small, all subjects go to the polls, and (ii) if the quorum is large, subjects in theex-antemajority group go to the polls, whereas subjects in theex-anteminority group tend to abstain. As a result, if the quorum is large, it frequently happens that the outcome is rendered invalid because of low voter turnout. Furthermore, when the number of subjects in each referendum increases, subjects of theex-anteminority abstain more aggressively, and there arises room for theex-postminority to win if the expected number of members is similar between the two groups. Therefore, if policy makers would like to avoid the possibility of strategic abstention, then our results suggest that they should impose either no quorum or only a relatively small quorum which most voters expect will be dwarfed by the actual turnout. If policy makers also care about the possible determination of eitheryesornowith extremely low voter turnout, as well as strategic abstention, then a relatively small quorum is recommended.