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Math 210G Mathematics Appreciation Dr. Joe Lakey Lecture 9: Su Voto es Su Voz. [The president is elected by ]. [Popular vote] [Electoral college] [Who has the most money] [Who has the most popular running mate]. SNL on Romney – Obama youtube version youtube second version.
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Math 210G Mathematics AppreciationDr. Joe LakeyLecture 9: Su Voto es Su Voz
[The president is elected by ] • [Popular vote] • [Electoral college] • [Who has the most money] • [Who has the most popular running mate]
SNL on Romney – Obama • youtube version • youtube second version
Electoral college • Each state is allocated as many electors as it has Representatives and Senators in the United States Congress.
Predicting outcomes • 538 • Vegas oddsmaker's view
[Who ran against G.W. Bush in 2000] • [Clinton] • [Hart] • [Quail] • [Gore]
Close U.S. Presidential elections • Close presidential races are nothing new • Electoral college history: idea based on lack of mass media • Three times elected president lost popular vote (Hayes, Harrison, G.W. Bush) • Changing the system not perceived to be in the best interest of the states.
Historical observation… • GOP almost always wins “toss-ups” • Counting these puts Romney at 257 and Obama at 281. • If Romney were to win Ohio, this would put Romney at 257+18=275 and Obama at 281-18=263. • Obama strategy should be… (1) Ohio, Ohio Ohio and try to nail down (2) try to swing Virginia, Colorado (3) nail down Nevada, Iowa Wisconsin (4) don’t forget CA.
(Penrose)-Banzhaf-(Coleman) power index • Banzhaf, John F. (1965), "Weighted voting doesn't work: A mathematical analysis", Rutgers Law Review 19(2): 317-343 • Example (Game Theory and Strategy P. D. Straffin): • [6; A:4, B:3, C:2, D:1] • 6 votes to pass, possible majorities: • AB, AC, ABC, ABD, ACD, BCD, ABCD • 12 total swing votes. • A = 5/12 B = 3/12 C = 3/12 D = 1/12
The Banzhaf Power Index: a mathematical representation of how likely a single state would be able to swing the vote • Larger states have more power • Is the electoral college fair? • Does it reflect popular opinion?
The Banzhaf Power Index (Bachrach et al 08) • Pivotal (critical) agent in a winning coalition is an agent that causes the coalition to lose when removed from it • The Banzhaf Power Index of an agent is the portion of all coalitions where the agent is pivotal (critical)
The Shapley-Shubik Index • The portion of all permutations where the agent is pivotal • Direct application of the Shapley value for simple coalitional games • Applies in situations in which one vote might precede another.
Banzhaf calculator for electoral college • General Banzhaf calculator
Daily electoral map • “Conditional expectation” • How does the power index change when we fix the weights for all states not considered battleground states? • Can New Mexico determine the outcome of the election?
Battleground states 2012 • RCP Poll Average Electoral Votes States Obama Romney Obama Romney • Colo. 47.6% 47.8% 0 9 • Fla. 47.0% 48.7% 0 29 • Iowa 48.8% 46.8% 6 0 • Nev. 49.5% 46.8% 6 0 • N.H. 48.2% 47.4% 4 0 • N.C. 44.7% 50.3% 0 15 • Ohio 47.9% 45.8% 18 0 • Va. 48.0% 48.0% 0 13 • Wis. 49.5% 46.8% 10 0 • Swing-State Votes 44 66 • Leaning/Likely State Votes 237 191 • Total Overall Votes 281 257
Banzhaf calculation • Can NM swing the vote? • [37; CO(9) FL (29) IA (6) NV (6) NH (4) NC (15) H (18) VA (13), WI (10), NM(5)] • Other states: 233 to 191. Obama needs 37 from swing + NM
VA+OH+NM forms a winning coalition for Obama[37; CO(9) FL (29) IA (6) NV (6) NH (4) NC (15) H (18) VA (13), WI (10), NM(5)] • True • False
All but FL and NC and VA forms a winning coalition for Obama[37; CO(9) FL (29) IA (6) NV (6) NH (4) NC (15) H (18) VA (13), WI (10), NM(5)] • True • False
[If you were to vote today, who would you choose for president] • Gary Johnson/Jim Gray • Romney/Ryan • Obama/Biden • Other • Undecided
[Females only: If you were to vote today, who would you choose for president] • Gary Johnson/Jim Gray • Romney/Ryan • Obama/Biden • Other • Undecided
[Males only: If you were to vote today, who would you choose for president] • Gary Johnson/Jim Gray • Romney/Ryan • Obama/Biden • Other • Undecided
[Does your vote matter?] • Yes • No
Is election fraud possible in America? • http://www.scoop.co.nz/stories/HL0310/S00211.htm