The prevalence and consequences of ballot truncation in ranked-choice elections
The prevalence and consequences of ballot truncation in ranked-choice elections
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DOI：
10.1007/s11127-019-00723-2
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发表时间：
2019-10-11
期刊：
影响因子：
1.6
通讯作者：
Foley, Angele M.
中科院分区：
文献类型：
--
作者：
Kilgour, D. Marc;Gregoire, Jean-Charles;Foley, Angele M.
在排名选择选举中，选民通过表明他们对候选人的偏好顺序来投票。当排序不完整时，投票被截断（称为部分投票）。有时候截断是被迫的选民只允许对有限数量的候选人进行排名，但有时候是自愿的。在计票过程中，当所有候选人都被淘汰时，截断的选票就被耗尽了。在最后阶段的胜利差距小于用尽选票数的单一获胜者选举中，选票用尽并因此被截断是一个令人关切的问题。这种关注激发了我们的研究。我们审查的证据，从实际的单一赢家排名选择选举，并得出结论，自愿选票截断是非常普遍的。此外，很难从战略上加以解释。为了评估选票截断的重要性，我们模拟了有四个，五个和六个候选人的排名选择选举，使用选民偏好的空间和随机模型。截断是否会改变孔多塞赢家赢得选举的概率？赢家是否会随着截断程度的增加而改变？我们发现，即使是少量的截断也会改变选举结果。
In ranked-choice elections, voters vote by indicating their preference orderings over the candidates. A ballot is truncated when the ordering is incomplete (called partial voting). Sometimes truncation is forced-voters are allowed to rank only a limited number of candidates-but sometimes it is voluntary. During the vote tabulating process, a truncated ballot is exhausted when all of the candidates it ranks have been eliminated. Ballot exhaustion and, therefore ballot truncation, is a concern in single-winner elections when the margin of victory in the final stage is less than the number of exhausted ballots. That concern motivates our study. We review evidence from actual single-winner ranked-choice elections and conclude that voluntary ballot truncation is very common. Moreover, it is difficult to explain strategically. To assess the significance of ballot truncation, we simulate ranked-choice elections with four, five and six candidates, using both spatial and random models of voter preferences. Does truncation change the probability that a Condorcet winner wins the election? Does the winner change as the extent of truncation increases? We find that even small amounts of truncation can alter election outcomes.