Polling in a proportional representation system

We study the effects of opinion polls on election results in proportional representation systems. Moderate voters have preferences over the vote shares received by the parties so that an agent’s optimal voting decision might depend on the other agents’ behavior. A voter’s information about other voters’ behavior can be improved through a series of opinion polls. We show that the mass of undecided voters decreases monotonically with the number of polls, but may not necessarily disappear. Voters who remain undecided have centrist ideologies. On average a series of polls brings the society closer to complete information even though specific polls may push the election result away from the complete information case

Wisdom of the Crowd? Information Aggregation and Electoral Incentives

Elections have long been understood as a mean to encourage candidates to act in voters' interest as well as a way to aggregate dispersed information. This paper juxtaposes these two key features within a unified framework. As in models of electoral control, candidates compete for office by strategically proposing policy platforms. As in models of information aggregation, agents are not always informed about the policy which maximizes the electorate welfare. Candidates face a trade-off between acting in the electorate's best interest and maximizing their chance of being elected. We provide conditions under which electoral institutions encourage candidates' conformism---thereby stifling proper competition among ideas---and render information aggregation unfeasible in equilibrium. In extensions, we highlight that the new political failure we uncover cannot be fully resolved by liberalizing access to candidacy or reducing voter information

Voting systems that combine approval and preference

Abstract Information on the rankings and information on the approval of candidates in an election, though related, are fundamentally different-one cannot be derived from the other. Both kinds of information are important in the determination of social choices. We propose a way of combining them in two hybrid voting systems, preference approval voting (PAV) and fallback voting (FV), that satisfy several desirable properties, including monotonicity. Both systems may give different winners from standard ranking and nonranking voting systems. PAV, especially, encourages candidates to take coherent majoritarian positions, but it is more information-demanding than FV. PAV and FV are manipulable through voters' contracting or expanding their approval sets, but a 3-candidate dynamic poll model suggests that Condorcet winners, and candidates ranked first or second by the most voters if there is no Condorcet winner, will be favored, though not necessarily in equilibrium