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IEM's Accuracy in Presidential Races Cited

Current betting markets -- led by web sites such as, and -- may outperform opinion polls when it comes to predicting the outcome of the U.S. presidential election. In the last four presidential elections, according to a paper by Justin Wolfers of the University of Pennsylvania and Eric Zitzewitz of Stanford University. The UNIVERSITY OF IOWA'S IOWA ELECTRONIC MARKET has averaged an error margin of +/- 1.5 percent in the week before the vote, compared with +/- 2.1 percent for the Gallup polls. More recently, traders picked John Edwards as John Kerry's running mate two months before Kerry did. Science Now is the online presence of Science magazine.

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