Voting with Preferences over Margins of Victory


This paper analyzes a two-alternative voting model with the distinctive feature that voters have preferences over the support that each alternative receives, and not only over the identity of the winner. The main result of the paper is the existence of a unique equilibrium outcome with a very intuitive characterization: in equilibrium voters who prefer a higher support for one of the alternatives vote for such alternative. Its computation is equally simple: the equilibrium outcome is the unique fixed point of the connected survival function associated to the distribution of the electorate. This characterization works for electorates with a finite number of citizens as well as with a continuum of agents, and for scenarios with and without abstention. Finally, strategic voting (voting for the least preferred alternative) is common for a fraction of the electorate who favor electorally "balanced" results.

Published as: Voting with Preferences Over Margins of Victory in Mathematical Social Sciences , Vol. 56, No. 3, 355--365, January, 2008