Information Aggregation in Polls

We study information transmission via polling. A policymaker polls constituents, who differ in their information and ideology, to determine policy. Full revelation is an equilibrium in a poll with a small sample, but not with a large one. In large polls, full information aggregation can arise in an equilibrium where constituents endogenously sort themselves into centrists, who respond truthfully, and extremists, who do not. We find polling statistics that ignore strategic behavior yield biased estimators and mischaracterize the poll's margin of error. We construct estimators that account for strategic behavior. Finally, we compare polls and elections.