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Wednesday, November 5, 2008

Prediction markets Predict Perfectly

It appears that when North Carolina and Missouri are finally officially called, McCain will have won Missouri, and Obama North Carolina. This will mean the final electoral tally will by 364 for Obama and 174 for McCain, if I'm not mistaken.
This will mean further that intrade.com will have exactly predicted - for days prior - the outcome of the US election. On caveat: intrade.com predicted Obama would win Missouri and McCain would win Indiana - it appears likely the opposite has occurred. But they both have 11 electoral votes so the net effect is intrade.com predicted perfectly.

"On the eve of the 2008 U.S. presidential election, Barack Obama and John McCain are making final arguments to voters in key swing states. Intrade's presidential markets show Obama extending his advantage even as polls show a slight tightening."


Barack Obama (364 Votes) (top)

John McCain (174 Votes) (bottom)

Florida (27)

80%

22%

Pennsylvania (21)

89%

11%

Ohio (20)

83%

20%

Georgia (15)

21%

75%

North Carolina (15)

70%

37%

Virginia (13)

86%

14%

Missouri (11)

51%

45%

Indiana (11)

41%

64%

Nevada (5)

82%

15%

New Mexico (5)

92%

11%

North Dakota (3)

29%

73%

Montana (3)

29%

79%

3 comments:

Anonymous said...

"...intrade.com predicted Obama would win Missouri and McCain would win Indiana - it appears likely the opposite has occurred"

You have an unusual concept of a "perfect prediction"

Garth A Brazelton said...

Well the net result of Electoral votes is the same, so in the end it doesn't matter. Both Missouri and Indiana were among the most heavily contested races. Maybe "perfect" is a strong word though I'll concede. How about "near-perfect," or "99% accurate"....

Anonymous said...

You economists. So focused on the outcome instead of the process or intermediate results. How about "96% accurate," since 4% of the states were predicted incorrectly? Or maybe you are awarding 75% for the final tally and 25% for individual state results?