Condorcet Breakdown and Strategic Voting in Simple Election Methods
Zender, Mia G.
2022
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We study several election methods, based on ranking or rating candidates. We focus on very simple methods only, since only very simple methods are likely to be adopted in practice. We ask two questions: 1. How likely is it that the method will fail to elect a Condorcet candidate? 2. How likely is it that there will be an opportunity for a group of voters to manipulate the election outcome through ... read moresuccessful “burying” of a candidate whom they see as the likely winner? We study these questions both numerically and analytically. Our results include:• Instant runoff (“ranked choice voting”) improves plurality voting in the sense that it substantially reduces the likelihood of failing to elect the Condorcet candidate. Neither instant runoff nor plurality voting ever allow successful burying.• The simple Condorcet-fair method studied here makes successful burying quite unlikely.• Voting based on mean rating (“range voting”) makes successful burying highly likely, and when the electorate is polarized, it also makes failure to elect the Condorcet candidate likely.• Voting based on median rating (“majority judgment”) makes failure to elect the Condorcet candidate unlikely. (We have no results on the likelihood of successful burying in majority judgment). In summary, among the methods we study here, the Condorcet-fair one appears to have the best properties. Majority judgment may be a good competitor, but we understand its properties less well at this point.
Thesis (B.S.)--Tufts University, 2022.
Submitted to the Dept. of Mathematics.read less - ID:
- pr76fk332
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