### Voting Behavior and Information Aggregation
in Elections with Private Information

October 1994

revised

August 1996

By

Timothy Feddersen and Wolfgang Pesendorfer

We analyze two-candidate elections in which voters are uncertain about
the realization of a state variable that affects the utility of all voters.
Each voter has noisy private information about the state variable. We show
that the fraction of voters whose vote depends on their private information
goes to zero as the size of the electorate goes to infinity. Nevertheless,
elections fully aggregate information in the sense that the chosen candidate
would not change if all private information were common knowledge. Equilibrium
voting behavior is to a large extent determined by the electoral rule, i.e.,
if a candidate is required to get at least x percent of the vote in order
to win the election then in equilibrium this candidate gets very close to
x percent of the vote with probability close to one. Finally, if the distribution
from which preferences are drawn is uncertain, then elections will generally
not satisfy full information equivalence and the fraction of voters who take
informative action does not converge to zero.