Bayesian Investor Blog

Once again, I feel somewhat humbled for underestimating the accuracy of presidential election markets. At least I was cautious enough to mainly bet against Bush winning states where he appeared to be behind, and against him winning 400 electoral votes, which made up for what I lost betting that Kerry would win the election and popular vote.

Assuming the preliminary results are accurately indicating the final results, Tradesports did quite well at predicting the elections (except for a few hours on Tuesday afternoon when it mistakenly reacted to exit polls). It’s Monday evening prices correctly indicated which presidential candidate would win each state. And it did a good job of indicating which states were closest (saying Iowa and Ohio were the least certain).

Judging by the home page on what seemed to be the best known site devoted to tracking the polls (electoral-vote.com), the final polls got Ohio, Florida, Iowa, Hawaii wrong and predicted a tie in New Mexico and New Hampshire. Other ways of interpreting the polls probably did better, but I didn’t track them.

Even using the Tradesports prices from a month before the election (October 2), Tradesports looks better than the final polls, getting only Wisconsin, New Mexico, and New Hampshire wrong, and showing Iowa and New Hampshire as the closest states.

Tradesports also had several contracts which did a good job of predicting the total electoral vote count, predicting a month in advance that Bush would get just under 300 electoral votes, and predicting on Monday evening that he would get about 276 electoral votes.

Tradesports predicted all but one senate race correctly. It was wrong on Alaska (which it said was the hardest to call). It looks like the pollsters called that one correctly. I haven’t checked whether pollsters missed any of the other Senate races.

Here are some of the prices I’ve saved, taken at approximately 9pm Pacific time on the indicated dates:

Date   Last  Bid  Ask   Contract Description
041101 97.3 97.1 98.0 G W Bush to gain ON or OVER 150 Electoral Votes
041101 92.0 91.5 92.0 G W Bush to gain ON or OVER 200 Electoral Votes
041101 71.5 71.5 72.0 G W Bush to gain ON or OVER 250 Electoral Votes
041101 23.2 23.2 23.5 G W Bush to gain ON or OVER 300 Electoral Votes
041101  9.0  7.6  9.2 G W Bush to gain ON or OVER 350 Electoral Votes
041101  3.9  2.6  4.0 G W Bush to gain ON or OVER 400 Electoral Votes
041101  2.0  1.7  3.0 G W Bush to gain ON or OVER 450 Electoral Votes
041101 51.2 51.2 53.0 George W Bush to receive the most Popular Votes
041101 48.9 46.2 48.9 John F Kerry to receive the most Popular Votes
041101  276  266  285 Number of Electoral Votes won by George W Bush
041101 53.4 53.2 53.4 George W Bush is re-elected as United States President.
041101 47.5 47.5 47.8 John Kerry to be elected as United States President
041101 97.3 95.3 99.6 G W Bush to win the electoral votes of Alabama
041101 97.0 95.0 99.8 G W Bush to win the electoral votes of Alaska
041101 92.0 91.0 92.5 G W Bush to win the electoral votes of Arizona
041101 85.0 81.1 85.0 G W Bush to win the electoral votes of Arkansas
041101  3.6  2.9  3.6 G W Bush to win the electoral votes of California
041101 76.0 75.3 76.0 G W Bush to win the electoral votes of Colorado
041101  3.0  1.2  5.5 G W Bush to win the electoral votes of Connecticut
041101  7.9  5.3  8.0 G W Bush to win the electoral votes of Delaware
041101 55.9 55.5 55.9 G W Bush to win the electoral votes of Florida
041101 97.0 97.0 99.6 G W Bush to win the electoral votes of Georgia
041101 26.8 26.2 28.4 G W Bush to win the electoral votes of Hawaii
041101 99.0 96.0 99.9 G W Bush to win the electoral votes of Idaho
041101  6.0  3.2  6.0 G W Bush to win the electoral votes of Illinois
041101 95.0 95.4 99.9 G W Bush to win the electoral votes of Indiana
041101 51.9 51.9 52.0 G W Bush to win the electoral votes of Iowa
041101 96.0 96.1 99.6 G W Bush to win the electoral votes of Kansas
041101 95.5 95.4 99.5 G W Bush to win the electoral votes of Kentucky
041101 95.0 95.0 99.0 G W Bush to win the electoral votes of Louisiana
041101  6.0  4.0  6.0 G W Bush to win the electoral votes of Maine
041101  5.0  3.1  5.0 G W Bush to win the electoral votes of Maryland
041101  2.0  0.4  3.0 G W Bush to win the electoral votes of Massachusetts
041101 22.0 22.0 23.5 G W Bush to win the electoral votes of Michigan
041101 27.0 20.0 29.0 G W Bush to win the electoral votes of Minnesota
041101 97.0 97.0 97.8 G W Bush to win the electoral votes of Mississippi
041101 87.2 87.1 91.6 G W Bush to win the electoral votes of Missouri
041101 98.0 98.0 99.9 G W Bush to win the electoral votes of Montana
041101 96.5 95.3 99.5 G W Bush to win the electoral votes of Nebraska
041101 74.9 74.0 75.0 G W Bush to win the electoral votes of Nevada
041101 31.5 31.5 34.0 G W Bush to win the electoral votes of New Hampshire
041101 13.0 11.1 14.0 G W Bush to win the electoral votes of New Jersey
041101 60.0 55.0 60.0 G W Bush to win the electoral votes of New Mexico
041101  2.1  1.7  3.1 G W Bush to win the electoral votes of New York
041101 95.0 92.1 95.1 G W Bush to win the electoral votes of North Carolina
041101 95.2 96.3 99.0 G W Bush to win the electoral votes of North Dakota
041101 55.0 51.4 55.0 G W Bush to win the electoral votes of Ohio
041101 99.6 95.0 99.6 G W Bush to win the electoral votes of Oklahoma
041101 10.0  8.5 10.0 G W Bush to win the electoral votes of Oregon
041101 28.9 25.0 28.9 G W Bush to win the electoral votes of Pennsylvania
041101  1.7  0.4  2.9 G W Bush to win the electoral votes of Rhode Island
041101 96.3 95.1 98.1 G W Bush to win the electoral votes of South Carolina
041101 95.3 96.3 99.9 G W Bush to win the electoral votes of South Dakota
041101 95.9 95.0 97.0 G W Bush to win the electoral votes of Tennessee
041101 96.0 96.0 99.8 G W Bush to win the electoral votes of Texas
041101 96.0 96.0 99.9 G W Bush to win the electoral votes of Utah
041101  2.6  0.6  4.7 G W Bush to win the electoral votes of Vermont
041101 90.1 90.2 93.3 G W Bush to win the electoral votes of Virginia
041101  5.9  5.9  6.0 G W Bush to win the electoral votes of Washington
041101 90.4 89.5 90.4 G W Bush to win the electoral votes of West Virginia
041101 44.0 44.1 46.9 G W Bush to win the electoral votes of Wisconsin
041101 97.6 95.2 99.9 G W Bush to win the electoral votes of Wyoming
041101  1.4  0.1  1.4 G W Bush to win the electoral votes of the District of Co
041101 96.3 94.0 97.4 Arlen Specter (R) of Pennsylvania to win re-election to U
041101 99.0 98.0 None Barack Obama(D) of Illinois to win election to US Senate
041101 97.0 98.2 98.8 Barbara Boxer(D) of California to win re-election to US S
041101 96.0 94.0 97.0 Barbara Mikulski(D) of Maryland to win re-election to US 
041101 95.5 93.0 98.0 Blanche Lincoln(D) of Arkansas to win re-election to US S
041101 23.0 18.0 23.0 Brad Carson (D) of Oklahoma to win election to US Senate
041101 96.5 94.0 99.0 Byron Dorgan(D) of North Dakota to win re-election to US 
041101 96.5 94.0 99.0 Charles Schumer(D) of New York to win re-election to US S
041101 94.5 92.0 97.0 Christopher Bond (R) of Missouri to win re-election to US
041101 96.5 94.0 99.0 Christopher Dodd(D) of Connecticut to win re-election to 
041101 96.5 94.0 99.0 Chuck Grassley (R) of Iowa to win re-election to US Senat
041101 94.5 92.0 97.0 Daniel Inouye(D) of Hawaii to win re-election to US Senat
041101 60.0 50.2 60.0 David Vitter (R) of Louisiana to win election to US Senat
041101 34.0 34.0 39.0 Erskine Bowles(D) of North Carolina to win election
041101 96.5 94.0 99.0 Evan Bayh(D) of Indiana to win re-election to US Senate
041101 95.5 93.0 98.0 George Voinovich (R)  of Ohio to win re-election to US Se
041101 97.0 95.0 99.0 Harry Reid(D) of Nevada to win re-election to US Senate
041101 89.0 82.0 89.0 Jim Bunning (R) of Kentucky to win re-election to US Sean
041101 90.0 87.5 None Jim DeMint(R) of South Carolina to be elected to US Senat
041101 96.5 94.0 98.8 John McCain (R) of Arizona to win re-election to US Senat
041101 96.0 95.0 99.0 Johnny Isakson(R) of Georgia to be elected to US Senate
041101 97.0 94.0 99.0 Judd Gregg (R) of New Hampshire to win re-election to US 
041101 46.0 44.0 46.0 Lisa Murkowski (R) of Alaska to win re-election to US Sen
041101 65.0 56.1 65.0 Mel Martinez (R) to win election to US Senate
041101 96.5 94.0 99.0 Mike Crapo(R) of Idaho to win re-election to US Senate
041101 96.5 94.0 99.0 Patrick Leahy(D) of Vermont to win re-election to US Sena
041101 95.0 90.0 95.0 Patty Murray(D) of Washington to win re-election to US Se
041101 34.0 33.0 34.0 Pete Coors(R) of Colorado to be elected to US Senate
041101 96.5 94.0 99.0 Richard Shelby (R) of Alabama to win re-election to US Se
041101 96.5 94.0 99.0 Robert Bennett(R) of Utah to win re-election to US Senate
041101 96.0 96.0 97.0 Ron Wyden(D) of Oregon to win re-election to US Senate
041101 95.2 93.0 98.0 Russell Feingold(D) of Wisconsin to win re-election to US
041101 96.5 94.0 99.0 Sam Brownback (R) of Kansas to win re-election to US Sena
041101 43.0 40.0 44.0 Tom Daschle(D) of South Dakota to win re-election to US S

041002 97.0 95.1 98.9 G W Bush to gain ON or OVER 150 Electoral Votes
041002 92.0 91.1 95.0 G W Bush to gain ON or OVER 200 Electoral Votes
041002 77.0 74.2 77.0 G W Bush to gain ON or OVER 250 Electoral Votes
041002 40.0 41.0 45.0 G W Bush to gain ON or OVER 300 Electoral Votes
041002 15.0 12.0 14.9 G W Bush to gain ON or OVER 350 Electoral Votes
041002  4.2  3.2  5.2 G W Bush to gain ON or OVER 400 Electoral Votes
041002  2.0  1.0  3.0 G W Bush to gain ON or OVER 450 Electoral Votes
041002 57.0 59.0 60.0 George W Bush to receive the most Popular Votes
041002 42.9 41.2 43.3 John F Kerry to receive the most Popular Votes
041002  300  282  300 Number of Electoral Votes won by George W Bush
041002 62.0 61.0 62.0 George W Bush is re-elected as United States President.
041002 38.0 38.1 39.9 John Kerry to be elected as United States President
041002 96.0 94.0 99.9 G W Bush to win the electoral votes of Alabama
041002 97.0 95.0 98.0 G W Bush to win the electoral votes of Alaska
041002 82.0 83.0 87.0 G W Bush to win the electoral votes of Arizona
041002 85.0 83.0 86.9 G W Bush to win the electoral votes of Arkansas
041002  8.5  8.3  9.9 G W Bush to win the electoral votes of California
041002 80.0 75.0 80.0 G W Bush to win the electoral votes of Colorado
041002  7.0  5.0 10.0 G W Bush to win the electoral votes of Connecticut
041002 13.5 13.0 13.8 G W Bush to win the electoral votes of Delaware
041002 63.0 63.0 64.0 G W Bush to win the electoral votes of Florida
041002 97.0 95.0 97.0 G W Bush to win the electoral votes of Georgia
041002  8.0  7.5  8.0 G W Bush to win the electoral votes of Hawaii
041002 97.0 94.0 98.0 G W Bush to win the electoral votes of Idaho
041002  8.2  6.5  8.9 G W Bush to win the electoral votes of Illinois
041002 96.0 94.0 98.5 G W Bush to win the electoral votes of Indiana
041002 58.0 57.0 59.0 G W Bush to win the electoral votes of Iowa
041002 94.0 94.5 97.0 G W Bush to win the electoral votes of Kansas
041002 90.0 89.0 92.0 G W Bush to win the electoral votes of Kentucky
041002 94.0 94.0 96.0 G W Bush to win the electoral votes of Louisiana
041002 22.0 22.1 27.0 G W Bush to win the electoral votes of Maine
041002 15.0 15.0 19.0 G W Bush to win the electoral votes of Maryland
041002  2.0  0.4  4.0 G W Bush to win the electoral votes of Massachusetts
041002 26.0 25.0 29.5 G W Bush to win the electoral votes of Michigan
041002 35.0 35.2 37.0 G W Bush to win the electoral votes of Minnesota
041002 96.0 94.0 98.0 G W Bush to win the electoral votes of Mississippi
041002 84.0 82.7 86.0 G W Bush to win the electoral votes of Missouri
041002 95.0 94.0 95.9 G W Bush to win the electoral votes of Montana
041002 95.0 95.0 98.0 G W Bush to win the electoral votes of Nebraska
041002 70.2 73.5 75.0 G W Bush to win the electoral votes of Nevada
041002 53.0 53.1 57.9 G W Bush to win the electoral votes of New Hampshire
041002 19.0 18.6 21.9 G W Bush to win the electoral votes of New Jersey
041002 35.0 36.0 39.0 G W Bush to win the electoral votes of New Mexico
041002  7.5  7.0  8.4 G W Bush to win the electoral votes of New York
041002 90.0 90.0 92.0 G W Bush to win the electoral votes of North Carolina
041002 96.0 94.1 99.0 G W Bush to win the electoral votes of North Dakota
041002 67.1 67.1 69.8 G W Bush to win the electoral votes of Ohio
041002 97.0 95.0 99.0 G W Bush to win the electoral votes of Oklahoma
041002 25.0 25.0 29.9 G W Bush to win the electoral votes of Oregon
041002 33.3 34.2 36.5 G W Bush to win the electoral votes of Pennsylvania
041002  4.0  2.0  6.0 G W Bush to win the electoral votes of Rhode Island
041002 95.0 94.0 95.0 G W Bush to win the electoral votes of South Carolina
041002 96.0 94.0 98.0 G W Bush to win the electoral votes of South Dakota
041002 88.0 88.5 90.0 G W Bush to win the electoral votes of Tennessee
041002 97.5 97.5 99.9 G W Bush to win the electoral votes of Texas
041002 97.0 95.0 99.9 G W Bush to win the electoral votes of Utah
041002  8.0  7.0  9.9 G W Bush to win the electoral votes of Vermont
041002 87.0 86.5 87.5 G W Bush to win the electoral votes of Virginia
041002 18.5 18.0 23.0 G W Bush to win the electoral votes of Washington
041002 81.0 81.0 83.0 G W Bush to win the electoral votes of West Virginia
041002 62.5 59.0 63.9 G W Bush to win the electoral votes of Wisconsin
041002 97.0 95.0 99.9 G W Bush to win the electoral votes of Wyoming
041002  2.0  0.1  2.0 G W Bush to win the electoral votes of the District of Co