Ex Interim Voting: An Experimental Study of Referendums for Public-Good Provision

We report the results of an experimental study that compares voting mechanisms in the provision of public goods. Subjects can freely decide how much they want to contribute. Whether the public good is finally provided is decided by a referendum under full information about all contributions. If provision is rejected, contributions are reduced by a fee and reimbursed. We compare unanimity with majority voting and both with the baseline of cheap talk. Contributions are highest under unanimity. Yet, results concerning overall efficiency are mixed. When provision occurs, only unanimity enhances efficiency. Overall, however, unanimity leads to too many rejections.