Content code
m1415
Slug (identifier)
voting-procedures
Parent content
Grades
Secondary V
Topic
Mathematics
Tags
Condorcet Method
preferential voting
Content
Contenu
Content
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Voting procedures consist of using a specific method to determine the victor or the winner of the vote.

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Voting procedures are tools that enable decision-making in the context of social choice. They are used to elect a winner among the candidates at the time of an election. There are different voting procedures. These will be illustrated by comparing similar situations.

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Title (level 2)
Majority Rule
Title slug (identifier)
majority-rule
Contenu
Content
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The winner is the candidate who obtains more than half of the votes, or in other words, the absolute majority.

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Also known as majority rule, this method has the advantage of being simple and quick to implement. It can, however, result in the election of a candidate who is disliked by a portion of the electorate, but this portion will always be less than |50\%.|

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Secondary 5 students from a school voted for their favourite of four winter activities. The following table shows the results of the vote.

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Activity

Votes collected

Snowboarding

|109|

Alpine skiing

|147|

Sledding

|23|

Skating

|66|

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Under majority rule, no activity wins this vote. To win, an activity would have to receive more than |50\%| of the vote (|173| or more votes out of |345|).

Title (level 2)
Plurality Voting
Title slug (identifier)
plurality-voting
Contenu
Content
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The winner is the candidate who wins the greatest number of votes, or in other words, the relative majority.

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This method has the advantage of being simple and quick to implement. However, it can lead to the election of a candidate who displeases a large portion of the electorate.

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Secondary 5 students from one school voted for their favourite of four winter activities. The following table shows the results of the vote.

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Activity

Votes collected

Snowboarding

|109|

Alpine skiing

|147|

Sledding

|23|

Skating

|66|

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According to plurality voting, alpine skiing wins because it received the most votes.

Title (level 2)
Borda Count
Title slug (identifier)
borda-count
Contenu
Content
Corps

Each voter ranks the candidates according to their order of preference. If there are |n| candidates, |n| points are awarded to the 1st choice of each voter, |n-1| points to the 2nd choice, and so on, until only a single point is granted to the last choice. The candidate who obtains the highest number of points wins.

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The advantage of this method is that it allows for a closer interpretation of the votes. Furthermore, this means it is possible to choose a candidate who has a high degree of voter satisfaction. However, it is complex to implement.

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The following table shows who should be awarded the title of the kindest teacher in a school according to Secondary 5 students.

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Choice

|\boldsymbol{112}| students

|\boldsymbol{73}| students

|\boldsymbol{42}| students

1st choice

Mr. Poulin

Ms. Drolet

M. Gauthier

2nd choice

Mr. Gauthier

Mr. Gauthier

Ms. Drolet

3rd choice

Ms. Drolet

Mr. Poulin

Mr. Poulin

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Given that the contest is between |3| candidates, if we use the Borda count method, each is awarded |3| points for a 1st choice vote, |2| points for a 2nd choice vote and |1| point for a 3rd choice vote.

The following table shows the number of points received by each candidate.

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Candidate

Points received

Mr. Poulin

|451\ \text{points} = (112\times 3 + 73 \times 1 + 42 \times 1)|

Ms. Drolet

|415\ \text{points} = (112 \times 1 + 73 \times 3 + 42 \times 2)|

Mr. Gauthier

|496\ \text{points} = (112 \times 2 + 73 \times 2 + 42 \times 3)|

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According to the Borda count, Mr. Gauthier is the nicest teacher in the school, since he received the most points.

Title (level 2)
The Condorcet Method
Title slug (identifier)
condorcet-method
Contenu
Content
Corps

Each voter ranks the candidates in order of preference. To win, a candidate must defeat all the other candidates in a one-on-one confrontation.

The candidates are compared by recording the number of votes obtained by head-to-head matchups.

The winner is the person who won all of his matchups against the other candidates.

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This method has the advantage of allowing for a closer, more nuanced interpretation of the results of a vote. Furthermore, this makes it possible to choose a candidate who has a high degree of voter satisfaction. However, it is complex to implement.

Content
Corps

The following table shows who should be awarded the title of the kindest teacher in a school according to Secondary 5 students.

Corps

Choice

|\boldsymbol{112}| students

|\boldsymbol{73}| students

|\boldsymbol{42}| students

1st choice

Mr. Poulin

Ms. Drolet

Mr. Gauthier

2nd choice

Mr. Gauthier

Mr. Gauthier

Ms. Drolet

3rd choice

Ms. Drolet

Mr. Poulin

Mr. Poulin

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  • |115| students |(73+42)| prefer Ms. Drolet to Mr. Poulin, while |112| prefer Mr. Poulin to Ms. Drolet. Ms. Drolet is therefore the winner of this matchup.

  • |115| students |(73+42)| prefer Mr. Gauthier to Mr. Poulin, while |112| prefer Mr. Poulin to Mr. Gauthier. Mr. Gauthier is therefore the winner of this matchup.

  • |154| students |(112+42)| prefer Mr. Gauthier to Ms. Drolet, while |73| prefer Ms. Drolet to Mr. Gauthier. Mr. Gauthier is therefore the winner of this matchup.

So, according to the Condorcet method, Mr. Gauthier is the nicest teacher in the school.

Title (level 2)
Elimination Voting
Title slug (identifier)
elimination-voting
Contenu
Corps

Elimination voting is also called the runoff method.

Content
Corps

To win, the candidate must obtain an absolute majority of votes, which means more than half of the votes. If this does not happen, proceed as follows.

  • First, eliminate the candidate with the fewest votes as a 1st choice and distribute these votes to the following candidate.

  • In the second step, a new count is made to designate first place. If a candidate then obtains the majority of the votes, they are the winner. Otherwise, the procedure starts again from the first step.

Content
Corps

The following table shows who should be awarded the title of the kindest teacher in a school according to Secondary 5 students.

Corps

Choice

|\boldsymbol{112}| students

|\boldsymbol{73}| students

|\boldsymbol{42}| students

1st choice

Mr. Poulin

Ms. Drolet

Mr. Gauthier

2nd choice

Mr. Gauthier

Mr. Gauthier

Ms. Drolet

3nd choice

Ms. Drolet

Mr. Poulin

Mr. Poulin

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If we use elimination voting, we first observe that no one receives more than half of the votes for the 1st choice.

Mr. Gauthier must be eliminated, since he received the fewest 1st-place votes, that is, |42| votes.

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​Choice

|\boldsymbol{112}| students

|\boldsymbol{73}| students

|\boldsymbol{42}| students

​1st Choice

​Mr. Poulin

​Ms. Drolet

​Mr. Gauthier

​2nd Choice

​Mr. Gauthier

​Mr. Gauthier

​Ms. Drolet

​3nd Choice

​Ms. Drolet

​Mr. Poulin

​Mr. Poulin

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Mr. Gauthier's 1st-choice votes are then attributed to Ms. Drolet, because she is the 2nd most preferred candidate in the list. After redistributing the votes, Mr. Poulin still holds |112| 1st-choice votes, but Ms. Drolet now has |115| |(73+42).|

Therefore, according to elimination voting, Ms. Drolet gets the award for being the kindest teacher in the school.

Title (level 2)
Approval Voting
Title slug (identifier)
approval-voting
Contenu
Content
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Each voter votes only once, but for as many candidates as they wish. The candidate who obtains the most votes wins.

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Four candidates ran in an election: Julian, Simon, Emilie and Claudine. Each voter can vote for more than one candidate if they wish. Here are the results of the vote.

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Number of electors who voted
for this or these candidate(s)

|\boldsymbol{45}|

|\boldsymbol{32}|

|\boldsymbol{28}|

|\boldsymbol{23}|

 

Julian

Simon

Julian

Julian

 

Emilie

Claudine

Simon

 

 

 

Emilie

Claudine

 

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Julian received |96| votes |(45+28+23),| Simon received |60| votes |(32+28),| Claudine received |60| votes |(32+28)| and Emilie received |77| votes |(45+32).|

According to approval voting, Julian wins the election.

Title (level 2)
Proportional Representation
Title slug (identifier)
proportional-representation
Contenu
Content
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The decision-making weight is distributed among the possible choices in proportion to the number of votes obtained.

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The proportional system takes into account each vote in the seat allocation. Moreover, the distribution of the elected officials represents the will of the voters fairly accurately. However, the disadvantage of this method is the possibility of creating a minority government. The need to form coalitions can then slow down the decision-making process.

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A city decides to allocate |10| seats on the city council. Three parties are running for election. Here are the results of the vote.

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Left

Votes collected

A

|15\ 235|

B

|23\ 429|

C

|2893|

Total

|\boldsymbol{41\ 557}|

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The number of seats allocated to each party can be calculated as follows.

  • Party A: |\dfrac{15\ 235}{41\ 557}\times10\approx3.67|
    So Party A will have at least |3| seats.

  • Party B: |\dfrac{23\ 429}{41\ 557}\times10\approx5.64|
    So Party B will have at least |5| seats.

  • Party C: |\dfrac{2893}{41\ 557}\times10\approx0.7|
    So Party C will not have any seats from the start.

Therefore, |8| seats are already allocated (|3| to party A and |5| to party B). The other |2| seats are allocated by placing the remainders (the decimals) in ascending order. Party C |(0.7)| will have one seat and Party A |(0.67)| will have the last seat.

So, according to proportional representation, Party A will have |4| seats, Party B will have |5| and Party C will have only one.

Title (level 2)
See Also
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see-also
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