Voting Methods and Fairness Criteria



Here's what we know, and for several cases, how we know it:


Majority Criterion
Condorcet Criterion
Monotonicity Criterion
Independence of
Irrelevant Alternatives
Criterion
Plurality Election
Satisfies
Fails
(1992 Presidential
 election example)
Satisfies
Fails
(1992 Presidential
 election example)
Borda Count
Fails
(Worksheet 1.2
example)
Fails
(Anything failing Majority
Criterion must also fail
Condorcet Criterion)
Satisfies
(See argument)
Fails
(See example)
Plurality-with-Elimination
Satisfies
(See argument)
Fails
(See exercise 33)
Fails
(Olympic Host City
selection example 1.10)
Fails
(See example)
(Advocates of Instant-Runoff
elections will point out the
failure is rare in practice.)
Pairwise Comparison
Satisfies
Satisfies
(A Condorcet
Candidate wins every
pairwise comparison)
Satisfies
Fails
(NFL Draft
example 1.12)


Last Modified January 24, 2007.
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