11A Does
the Majority always rule?
Voting with 2 choices
majority rule: the winner is the candidate
receiving more than 50% of the vote.
Properties:
- every vote has the same weight
- symmetry between candidates
- if a vote for the loser would be changed to a vote
for the winner, then no change of outcome.
US Presidential Elections
- popular vote reflects the total number of votes
received by each candidate
- president is elected by electoral vote
- each state has # of senators (2) +
# of representatives many electors
- electors belong to the party whose candidate won
the popular vote in the state (except for Nebraska and Maine). This is
a locally winner-takes-all system.
-
In 1976 Jimmy Carter won the presidency over Gerald Ford with 297 vs 240
electoral votes. The popular votes were 40,830,763 vs. 39,147,973 votes.
Contrast the numbers, what kind of percentages do they represent?
Variations of majority rule
- filibuster: Senators keep talking about a bill
they want to prevent until the filibuster is cut off. If the bill is to
pass now, it would need to get at least 3/5 or 60% of senate votes.
- international treaties need a 2/3 majority (super
majority) in the Senate.
- amendments to the Constitution require 2/3 majorities
in both House and Senate and then must be approved by 3/4 of the states.
- veto: a bill approved by simple majorities in the
House and the Senate can be vetoed by the President. It then needs 2/3
super majorities in both House and Senate to override the veto.
- propositions in state elections receiving huge
majorities can be declared unconstitutional by the courts.
- criminal law: need a 3/4 super majority to convict
otherwise "hung jury", dismissal of case or retrial.
-
Of the 100 US senators , 57 favor a new bill on health care reform.
The opposing senators start a filibustger. Is the bill likely to pass?
-
A criminal conviction in a particular state requires a vote of 2/3 of the
jury members. On a 12 member jury, 7 jurors vote to convict. Will the defendant
be convicted?
-
A proposed amendment to the US Constitution has passed both the House and
the Senate with more than the required 2/3 super majority. Each state holds
a vote on the amendment, and it receives a majority vote in all but 15
of the 50 states. Is the constitution amended?
-
A tax increase bill has the support of 70 out of 100 senators and 260 out
of 435 members of the House of Representatives. The president promises
to veto the bill. Is it likely to become law?
Voting with 3 or more choices
plurality: winner is choice with most
votes ( not necessarily the majority of votes).
runoff: new vote between top vote
getters.
1992 election results:
|
Popular Vote |
Popular Percentage |
Electoral Vote |
Electoral Percentage |
Clinton |
44,909,889 |
43.3 |
370 |
68.8 |
Bush |
39,104,545 |
37.7 |
168 |
31.2 |
Perot |
19,742,267 |
19.0 |
0 |
0 |
Total |
103,756,701 |
100 |
538 |
100 |
If 65% of the Perot votes had voted for Bush, Bush would have won.
Preference Schedules rank candidatges
in order of preference
Ballot |
|
1st choice |
B |
2nd choice |
E |
3rd choice |
D |
4th choice |
C |
5th choice |
A |
used in: Heisman Trophy, beauty pageants, Academy Awards, sports awards
-
How many possible rankings can there be for 5 candidate elections?
First |
A |
B |
C |
D |
E |
E |
Second |
D |
E |
B |
C |
B |
C |
Third |
E |
D |
E |
E |
D |
D |
Fourth |
C |
C |
D |
B |
C |
B |
Fifth |
B |
A |
A |
A |
A |
A |
|
18 |
12 |
10 |
9 |
4 |
2 |
Ways of deciding the outcome of an election
- plurality:
winner is the candidate with most first place votes.
A wins
- single runoff:
runoff between the 2 candidates who got the most first place votes.
B wins
- sequential runoff:
repeat until only 1 candidate is left:
eliminate the candidate with the fewest first place
votes
recalculate the table without that candidate
C wins
- point system
(e.g. Borda count) ( used in College
football polls)
with 5 candidates, the first
place earns 5 points, 2nd place earns 4 pts, etc.
the winner is the candidate
with the largest number of points.
D wins
- pairwise comparison
(Condorcet method)
The candidate who wins the
most pairwise contests wins.
E wins
Condorcet
Paradox:
First |
A |
C |
B |
Second |
B |
A |
C |
Third |
C |
B |
A |
|
14 |
12 |
10 |
A beats B in 26/36 votes
B beats C in 24/36 votes
C beats A in 22/36 votes
who wins?
-
17
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