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Chapter 12 sec 1. Def. Each person votes for his or her favorite candidate. The candidate receiving the most votes is declared the winner.

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Presentation on theme: "Chapter 12 sec 1. Def. Each person votes for his or her favorite candidate. The candidate receiving the most votes is declared the winner."— Presentation transcript:

1 Chapter 12 sec 1

2 Def. Each person votes for his or her favorite candidate. The candidate receiving the most votes is declared the winner.

3 Plurality method is the simplest way to determine the outcome of an election; Many state and local elections use the plurality method because it is easy to determine the winner.

4 The students have organize a union in order to improve their salaries and working conditions. A group of 33 students, have just had and election to choose their president. Using the plurality method, who won the election?

5 Ann 10 Ben 9 Mike 11 Zach 3

6 Mike won, for he had the most votes. Mike won the election even though 22/33 = 66.7% of the group voted against him.

7 Permits the voter to “fine-tune” his or her vote in the sense that the voter can designate not only a first choice but also a second choice, a third choice, and so on.

8 In the previous election, we could have used the Borda Method by specifying that on the voter’s ballot the first choice would be 4 points, the second choice 3 points, third choice 2 points, and the fourth choice 1 point.

9 Def. If there are k candidates in an election, each voter ranks all candidates on the ballot. Then the first choice is given k pts, the second choice is given k-1 pts, the third choice is given k-2 pts, and so on. The candidate who receives the most total pts wins the election.

10 Preference675393 1 st MAMABZ 2 nd AMZZAA 3 rd BBBBZM 4 th ZZAMMB The top numbers are the number of people that voted in the particular preference ballot. The first column means that there were 6 people choose Mike first, Ann second, Ben third, and Zach fourth.

11 To determine the winner we calculate the ballots. Ann = 10x4+18x3+0x2+5x1 = 99 pts Ben = 9x4+0x3+21x2+3x1 = 81 pts Mike = 11x4+7x3+3x2+12x1 = 83 pts Zach = 3x4+8x3+9x2+13x1 = 67 pts

12 We notice that Ann wins the election. Many polls use the Borda to rank sports teams.

13 A WINS WITH 78 POINTS Preference 8757 1 st CDCA 2 nd AABD 3 rd BBDB 4thDCAC

14 Def. Each voter votes for on candidate. A candidate receiving a majority of votes is declared the winner. If no candidate receives a majority of votes, then the candidate(or candidates) with the fewest votes is dropped from the ballot and a new election is held. This process is continues until a candidate receives a majority of votes.

15 Viewing the first place, Zach has the fewest votes so he is eliminated. The remaining candidates move up. Preference675393 1 st MAMABZ 2 nd AMZZAA 3 rd BBBBZM 4 th ZZAMMB

16 By looking at the 3 rd column and the last column they are the same, therefore we can combine them. Preference675393 1 st MAMABA 2 nd AMBBAM 3 rd BBAMMB

17 Viewing the first row Ben has the fewest votes, therefore he is eliminated. Preference610539 1 st MAMAB 2 nd AMBBA 3 rd BBAMM

18 Combine the same columns together. Ann wins with 22 votes and Mike has 11 votes. Preference610539 1 st MAMAA 2 nd AMAMM

19 C wins Preference 89542 1 st CEBAA 2 nd ADCDC 3 rd BBEBB 4 th ECACE 5 th DADED

20 Def. Voters first rank all candidates. If A and B are a pair of candidates, we count how many voters prefer A to B and vise versa. Whichever candidate is preferred the most receives 1 pt. If A and B are tied, then each receives ½ pt. Do this comparison, assigning pts., for each pair of candidates. Candidates with the most pts wins.

21 You are a owner of a restaurant and want to add to its menu. You did a survey in which the customers were asked to rank their preferences for (B)urritos, (S)ushi, & (H)amburger.

22 We must compare : a) S with H, b) S with B, and c) H with B Preference2,1088641,1561,4611,5871,080 1 st SSHHBB 2 nd HBSBSH 3rdBHBSHS

23 A) S with H Comparing S with H, we will ignore all references to B 4, 559 prefer S over H 3, 697 prefer H over S Therefore we award S, 1 pt. Preference2,1088641,1561,4611,5871,080 1 st SSHHBB 2 nd HBSBSH 3rdBHBSHS

24 Compare S with B 4, 128 prefer S over B 4, 128 prefer B over S Therefore S and B are tied, so each receive ½ pt each. Preference2,1088641,1561,4611,5871,080 1 st SSHHBB 2 nd HBSBSH 3rdBHBSHS

25 Compare H and B 4, 725 prefer H over B 3, 531 prefer B over H Therefore award 1 point to H Preference2,1088641,1561,4611,5871,080 1 st SSHHBB 2 nd HBSBSH 3rdBHBSHS

26 S has 1½ pt H has 1 pt B has ½ pt Therefore the winner is S.

27 Use the pairwise comparison to determine the winner. Also list how many pts each item gets. H has 2 pts. B has 1 pt. S has 0 pts. Preference9858641,1561,0211,1871,080 1 st SSHHBB 2 nd HBSBSH 3rdBHBSHS


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