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David Strömberg


WH 2008 Analysis


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The material on this page was produced using the model described in the my article “How the Electoral College Influences Campaigns and Policy: The Probability of Being Florida” published in the June 2008 issue of the American Economic Review.

Topics

How the candidates will spend their time

The graph to the right shows how the model recommends candidates to visit states, if they wish to maximize the probability of winning the election. The estimates are based on opinion polls available September 10. After the top four – Florida, Ohio Pennsylvania, Michigan – follows a set of states which were much less important in the 2004 election: Virginia, Colorado and California. To a lesser extent, this also holds for New Jersey, Nevada, Arizona, Indiana and New Mexico. The importance of the states in 2008 relative to 2004 (measured in mid September) is plotted in Graph 2. States above the 45-degree line are more important in 2008 than in 2004.

Graph 2. Expected visit shares in 2008 relative to 2004

 

Have Obama and McCain
visited states to maximize their win probabilities?

To see how well the model explains the 2008 candidates’ visits so far, I downloaded data on campaign visits from the New York Times web site. The correlations between the actual and equilibrium visits are 0.9 for Obama and 0.8 for McCain (who spent a lot of time in New York). Graph 3 shows the actual and predicted visits.

Graph3.
Expected visits and actual Obama + McCain visits August-September.

Forecasted votes, win probabilities, and campaign importance of states

Table 1 contains a set of statistics based on 100,000 simulated election outcomes, based on data from September 10. See here for a description of the simulation procedure and how to run your own simulations. The first column is the forecasted Democratic share of the two-party vote. The second is the probability that the Democrats will win the state. The third column is the probability that the Democrats get between 49 and 51 percent of the votes in the state, at the same time as the state decides the election outcome (in the sense that, ex post, moving the state from one candidate’s column to the other’s changes who wins the presidency). This is what happened in Florida in 2000, and (almost) in Ohio in 2004. The third column shows the probability of this happening in 2008 for the different states based on the information available September 10. Qs is essentially the same number (see paper), computed using an analytical formula from the equilibrium condition of presidential candidates maximizing their win probabilities. 

Table 1. State statistics

 

Forc. Dem.vote

Dem. win probability

Decisive
Swing State

Qs

Florida

49.27

41.1

5.26

4.93

Ohio

50.10

51.2

4.42

4.37

Pennsylvania

53.26

83.7

3.55

3.53

Michigan

52.87

80.6

3.11

2.96

Virginia

48.46

32.2

2.13

2.17

Colorado

50.64

57.6

2.00

1.90

California

56.70

97.9

1.97

1.45

Wisconsin

53.04

82.1

1.69

1.59

Missouri

47.66

24.3

1.43

1.49

New Mexico

50.90

60.7

1.10

0.96

Nevada

51.02

62.1

1.09

0.98

New Jersey

55.44

95.0

1.05

1.01

Arizona

46.84

17.1

0.96

0.96

Iowa

54.00

88.6

0.88

0.77

Washington

55.30

94.6

0.82

0.74

Minnesota

55.20

94.2

0.78

0.73

New Hampshire

52.88

80.8

0.68

0.55

West Virginia

47.68

24.4

0.68

0.61

Arkansas

47.15

19.7

0.67

0.67

Oregon

55.59

95.4

0.44

0.41

Indiana

45.02

6.7

0.41

0.44

Illinois

57.62

98.9

0.38

0.34

Georgia

44.46

4.7

0.36

0.39

North Carolina

43.51

2.6

0.18

0.22

New York

59.00

99.7

0.17

0.17

Delaware

56.21

96.9

0.13

0.08

Louisiana

43.33

2.1

0.11

0.11

South Carolina

43.16

1.9

0.09

0.10

Tennessee

42.76

1.5

0.08

0.09

Texas

42.40

1.1

0.08

0.15

Connecticut

58.30

99.4

0.07

0.08

Maine

57.71

99.0

0.07

0.06

Mississippi

42.78

1.5

0.05

0.06

Maryland

59.26

99.7

0.05

0.05

Montana

43.40

2.3

0.04

0.04

Kentucky

41.61

0.6

0.02

0.03

North Dakota

41.97

0.8

0.01

0.02

South Dakota

41.65

0.6

0.01

0.01

Alabama

40.27

0.2

0.01

0.01

Hawaii

61.38

100.0

0.00

0.00

Kansas

39.28

0.1

0.00

0.00

Alaska

39.13

0.1

0.00

0.00

Utah

28.87

0.0

0.00

0.00

Wyoming

30.52

0.0

0.00

0.00

Vermont

65.39

100.0

0.00

0.00

Oklahoma

35.07

0.0

0.00

0.00

Nebraska

36.98

0.0

0.00

0.00

Idaho

33.61

0.0

0.00

0.00

Massachusetts

63.67

100.0

0.00

0.00

Rhode Island

63.87

100.0

0.00

0.00

District of Columbia

 

100.0

0.00

0.00

 

 

 


 
 
 


Graph 1. Share of candidate's expected visits in each state