Just over a year ago the Department of Defense cancelled
their program on using markets to predict future world events, an
overreaction that stopped funding a potentially powerful prediction tool. Robin
Hanson has a comprehensive web page
giving a history and plenty of links.
Information markets live in limited academic-based markets like the Iowa Electronic Market and
offshore sites like Tradesports. For example the current
price on Tradesports for Bush winning the election is 51.5 which
translates to a 0.515 probability that Bush will win indicating a very
close contest.
For each state, Tradesports has a security on whether Bush will win
that state. They also have some bundles of states. The price for
Florida is 50.1, Ohio 55.4 and Bush winning both Florida and Ohio is
47.1. This gives a surprising correlation between Florida and Ohio. If
you believe the theory there is a very high 0.94 probability that Bush
wins Ohio given that he wins Florida and with a 0.89 probability these
two very different swing states will go the same way.
Tradesports gives David Vitter a 59 percent chance of becoming a
senator from Louisiana. David Vitter is the brother of CS theorist and
former SIGACT chair Jeff Vitter.