MMW Lesson 6: Voting Methods

___________ is a method for a group, such as a meeting or an electorate, to make a collective decision or express an opinion usually following discussions, debates or election campaigns.

Voting

Democracies elect holders of high office by __________

voting

Voting is a ________________ and power that citizens in a democratic county exercise to select their leaders.

sacred right

________________ is a ballot which the voter ranks the choices in ORDER OF PREFERENCE

Preference ballot

_____________ refers to the list of choices of an individual

ballot

______________ is a table that provides information the number and how voter would rank the alternatives if their first choice was unsuccessful

Preference schedule

__________________

• Each voter votes for one candidate
• The candidate with the most votes wins
• The winning candidate does not have to have the majority vote (More than 50% of the total vote)
• In case of a tie, a special runoff election may be held
• Alternative choices are not considered

The plurality method of voting

_____________________

• Each person votes for a candidate
• Candidates who get the majority vote wins
• If no candidate gets the majority vote, the candidate with the fewest votes is eliminated and a new election is held
• The process repeats until a winner is declared
• Limitation: expensive and time consuming

Plurality with elimination without rank

______________________________________

• First, Eliminate the candidate with the fewest number of first-place voters • If two or more of the alternatives have the same number of first-place votes, all are eliminated unless that would eliminate all alternatives
• Adjust the rankings each time an elimination is done
• Repeat the process until only two candidates are left
• The candidate with the majority vote wins

Plurality with Elimination with Rank (Instant Runoff Method)

_______________________

• If there are n candidates or issues in an election, each voter ranks the candidates or issues by giving;
– n points to the voter’s first choice
– n-1 points to the second choice and so on
• The candidate with the greatest total points will win

Borda Count Method of Voting

__________________________

• Each candidate is compared one-on-one with each other (Head-to-Head method).
• A candidate receives one point for a win, 0.5 points for a tie, and 0 point for a loss.
• The candidate with the greatest number of points win the elections.

Pairwise Comparison Voting Method

What are the 4 Criterions under fairness criterion?

1. -

2. -

3. -

4. -

Majority criterion
Monotonicity criterion
Condorcet criterion
Independence of irrelevant alternatives criterion

___________________ is the type of criterion if there is a candidate that has MAJORITY of first-place votes, then that candidates is the winner of the election

Majority criterion

__________________ is the type of criterion if candidate A is a winner of an election, and in a re-election, all changes in the ballots are changes favorable only to A, then candidate A is the winner of the election

Monotonicity criterion

___________________ is the type of criterion if there is a candidate that is preferred by the voters over each of the other candidates (all possible head-to-head matchups), then that candidate is the winner of the election (or Condorcet candidate)

Condorcet criterion

_____________________ is the type of criterion if candidate A is a winner of an election, and (or more) of the other choices is disqualified/withdraw and the ballots recounted, then candidate A is still the winner

Independence of irrelevant alternatives criterion

___________________

• There is no voting method involving three or more choices that satisfies all four fairness criteria.
• It was proposed by _____________ in his 1951 book Social Choice and Individual Values

Arrow’s Impossibility Theorem
Kenneth Arrow