Voting Methods and Fairness Criteria
Voting rules convert individual preferences into collective outcomes. Different rules can select different winners even when voters' preferences remain unchanged.
Summary
Voting rules convert individual preferences into collective outcomes. Different rules can select different winners even when voters' preferences remain unchanged.
| Method | How preferences are counted |
|---|---|
| Plurality | Selects the candidate with the most first-choice votes. |
| Instant-runoff | Repeatedly eliminates the candidate with the fewest first-choice votes and transfers ballots to the next remaining preference. |
| Borda count | Awards points by rank, where is the number of candidates. |
🧠 Key Concepts
- Plurality
- Instant runoff voting
- Borda count
- Pairwise comparison
- Majority criterion
- Condorcet criterion
- Monotonicity
- Irrelevant alternatives independence
- Condorcet cycles
- Arrow's impossibility theorem
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Voting Methods and Fairness Criteria
📘 Overview Voting methods can produce different winners from the same voter preferences. Fairness criteria provide precise standards for evaluating these methods, but some desirable standards cannot all be satisfied simultaneously.
🧠 Key Idea A voting rule determines how individual preferences become a collective outcome. Evaluating that rule requires distinguishing how it counts preferences from which fairness criteria it satisfies.
⚔️ Core Details: - Plurality selects the candidate with the most first-choice votes. - Instant-runoff voting repeatedly eliminates the candidate with the fewest first-choice votes and transfers those ballots to the next remaining preference. - Borda count assigns
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