Exit poll surveys during elections are conducted to predict the outcome of actual elections. However, such polls historically have been controversial, particularly for multi-phase elections, because they can influence the behavior of voters in the later rounds of voting. If subsequent voters are more likely to vote for the predicted frontrunner, the effect is known as the bandwagon voting phenomenon, whereas if they vote for the predicted trailing candidate, the phenomenon is known as underdog voting. To avoid such issues, in 2009 the election administration in the world’s largest democracy (India) introduced a blanket ban on publishing exit polls in the media until all rounds of an election are completed. Exploiting the potentially exogenous timing of this reform, and using administrative data to compare states that went to elections before and after the ban, we find that in response to the policy, vote shares increased for the frontrunner and declined for others. The result implies that in the counterfactual, without the ban, fewer people would have voted for the frontrunner. The evidence is suggestive of underdog voting.

在选举期间进行出口民意调查是为了预测实际选举的结果。然而，此类民意调查在历史上一直存在争议，特别是对于多阶段选举，因为它们会影响选民在后期投票中的行为。如果随后的选民更有可能投票给预测的领先者，这种效应被称为随波逐流投票现象，而如果他们投票给预测的落后候选人，这种现象被称为失败者表决。为避免此类问题，2009 年，世界上最大的民主国家（印度）的选举管理部门全面禁止在所有轮次选举完成之前在媒体上发布出口民意调查。利用这项改革的潜在外生时机，并使用行政数据比较禁令前后参加选举的州，我们发现，为响应该政策，领先者的投票份额增加，其他人的投票份额下降。结果表明，在反事实的情况下，如果没有禁令，投票给领跑者的人会更少。证据表明投票失败。