Roll... to the White House

Final Results of the Election

  Obama McCain
Electoral Votes 365 173

Our Prediction

  Obama McCain
Probability of Winning 1.00 0.00
Probability of Getting 300 Electoral Votes 1.00 0.00
Expected Electoral Vote 356.3 181.7
Safe Electoral Votes* 338 157
Standard Deviation 11.24
*These are the sum of electoral votes where the candidate is almost certain to win (0.85 chance or better)

Our Closest Scenario

("Strong Democrat Swing")

  Obama McCain
Probability of Winning 1.00 0.00
Probability of Getting 300 Electoral Votes 1.00 0.00
Expected Electoral Vote 362.0 176.0
Safe Electoral Votes* 338 157
Standard Deviation 10.97
*These are the sum of electoral votes where the candidate is almost certain to win (0.85 chance or better)

How Did We Do?

The 2008 United States Presidential Election is now history, and our nation has elected Senator Barack Obama as the 44th President of the United States.

Our model predicted 50 of the 51 states (including the District of Columbia). In the Neutral scenario, the expected number of Electoral College votes for President-Elect Obama was 356.3, while 365 were actually captured. This discrepancy corresponds to an error of 0.77 standard deviations (based on a standard deviation of 11.24). The Strong Democrat Swing scenario was the closest to the actual results, predicting 362 Electoral College votes.

All 40 of the so-called non-battleground states were predicted correctly. The remaining 11 battleground states are analyzed in the following table:

State Actual Obama Percentage of Votes Actual McCain Percentage of Votes Predicted Obama Probability of Winning Predicted McCain Probability of Winning Correct?
Colorado 53% 46% 1.00 0.00 Yes
Florida 51% 49% 0.97 0.03 Yes
Indiana 50% 49% 0.27 0.73 No
Missouri 49% 50% 0.30 0.70 Yes
Montana 47% 50% 0.26 0.74 Yes
Nevada 55% 43% 1.00 0.00 Yes
New Mexico 57% 42% 1.00 0.00 Yes
North Carolina 50% 49% 0.71 0.29 Yes
North Dakota 45% 53% 0.25 0.75 Yes
Ohio 51% 47% 1.00 0.00 Yes
Virginia 52% 47% 1.00 0.00 Yes

All of these states, except Indiana, were correctly predicted. Of the five states with a 85% or lower probability of the leading candidate winning, four were correctly predicted. For the Strong Democrat Swing scenario, these five states are analyzed in the following table:

State Actual Obama Percentage of Votes Actual McCain Percentage of Votes Predicted Obama Probability of Winning Predicted McCain Probability of Winning Correct?
Indiana 50% 49% 0.43 0.57 No
Missouri 49% 50% 0.41 0.59 Yes
Montana 47% 50% 0.39 0.61 Yes
North Carolina 50% 49% 0.80 0.20 Yes
North Dakota 45% 53% 0.31 0.69 Yes

From these results, Indiana was the most difficult state to predict, closely followed by Missouri.

Thank you for visiting our web site. Look for Roll... to the White House in 2012!

This web site has been developed by computer science and political science students at the University of Illinois.

This research project has been supported in part by the National Science Foundation (IIS-0827540).
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