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Flashcards in Voting methods Deck (15)
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1

Plurality method

The candidate with the most first place votes wins. (Does not have to be majority)

2

Borda count method

Voters rank all candidates from most favorable to least. Each last place vote receives 1 pt, each next to last vote receives 2 pts and so on.
Candidate with most points wins.

3

Plurality-with-elimination method

Candidate with majority (over 50%) of 1st place votes wins. If no candidate receives majority, eliminate the candidate with fewest 1st place votes. Either hold another election or adjust preference table. Continue process until a candidate receives a majority of 1st place votes. That person wins.

4

Pairwise comparison method

Voters rank all candidates. Series of comparisons is made and each of the candidates is compared to each of the other candidates. Preferred candidate in each comparison receives 1 point. In case of a tie, each receives a half point. Candidate with most points wins.

5

Fairness Criteria (4)

1-Majority criterion
2-Head to head criterion
3-Monotonicity criterion
4- Irrelevant Alternatives criterion

6

Majority criterion

If a candidate receives a majority of 1st place votes, then that candidate should win.

7

Head to head criterion (Condorcet)

If a candidate is favored when compared head to head with every other candidate, then that candidate should win.

8

Monotonicity criteria

If a candidate wins an election, in a reelection, the only changes are changes that favor candidate, then that candidate should win reelection.

9

Irrelevant Alternatives criterion

If a candidate wins election, and in recount, the only changes are that one or more of other candidates are removed from ballot, then that candidate should still win election.

10

Arrow’s Impossibility theorem

It is mathematically impossible for any democratic voting system to satisfy each of the four fairness criteria.

11

Preference ballots

Ballots that rank candidates in order of preference

12

What voting method may not satisfy majority criterion?

Borda count method

13

Which voting methods may not satisfy Head-to-head criterion? (3)

Plurality method
Borda count method
Plurality with elimination method

14

Which voting methods may not satisfy monotonicity criterion? (3)

Borda count method
Plurality with elimination method
Pairwise comparison method

15

Which voting methods may not satisfy irrelevant alternatives criterion?

All:
Plurality
Borda count
Plurality with elimination
Pairwise comparison