A Study of Quadratic Voting

Abstract

Quadratic Voting (QV) is a promising technique for improving group decisionmaking by accounting for preference intensities. QV is a social choice mechanism in which voters buy votes for or against a proposal at a quadratic cost and the outcome with the most votes wins. In some cases, individuals are asymmetrically informed about the effects of legislation and therefore their valuations of legislation. For instance, anti-corruption legislation is the most beneficial to taxpayers and the most detrimental to corrupt officials when corruption opportunities are plentiful, but government officials have better information than taxpayers about how many corruption opportunities exist. I provide an example of a setting in a large population where QV does not achieve approximate efficiency despite majority voting achieving full efficiency. In this example, a society considers an anti-corruption policy that protects taxpayers from corruption by deterring corruption. Officials know whether corruption opportunities exist, but taxpayers are uncertain about whether corruption opportunities exist. I present surprising experimental results showing that in one case where theory predicts QV will perform poorly and majority voting will perform relatively well, QV performs much better than expected and is about as efficient as majority voting.

Keywords: Quadratic Voting, game theory