What are the best quorum rules? A laboratory investigation

Many political systems with direct democracy mechanisms have adopted rules preventing decisions from being made by simple majority rule. The device added most commonly to majority rule in national referendums is a quorum requirement. The two most common are participation and approval quorums. Such rules are responses to three major concerns: the legitimacy of the referendum outcome, its representativeness, and protection of minorities regarding issues that should demand a broad consensus. Guided by a pivotal voter model, we conduct a laboratory experiment to investigate the performances of different quorums in attaining such goals. We introduce two main innovations in relation to previous work on the topic. First, part of the electorate goes to the polls out of a sense of civic duty. Second, we test the performances of a different quorum, the rejection quorum, recently proposed in the literature. We conclude that, depending on the preferred criterion, either the approval or the rejection quorum is the best.