## [Computational Complexity] Prediction Map Post Mortem

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• As I ve mentioned before , David Pennock, Yiling Chen and I developed a map predicting the 2006 Senate races based on market prices from tradesports.com . So
Message 1 of 1 , Nov 9, 2006
As I've mentioned before, David Pennock, Yiling Chen and I developed a map predicting the 2006 Senate races based on market prices from tradesports.com. So how did those predictions go? In short you can say the markets predicted every individual race correctly but got the senate wrong, but let us look a little more carefully.

At about 9 AM CST on the morning of election day I made a snap shot of the map for a Discovery Channel Website article.

Every state colored blue was won by a democrat and every state colored red went to a republican. But also note the 69% given to GOP (Republican) Senate control although this election will give control to the democrats. No outcome would have made all the states and senate control agree with the 9 AM map.

Were the markets inconsistent? No, because the markets predict not absolutely but probabilistically. For example, the markets gave a probability of winning 60% for each of Virginia and Missouri and the democrats needed both to take the senate. If these races were independent events, the probability that the democrats take both is 36% or a 64% chance of GOP senate control assuming no other surprises.

Of course the races were not independent events and there are other states involved making it more difficult to compare the probabilities of the individual races with that of senate control.

So how did the markets do as predictors? Quite well as the outcome seems quite reasonable given the markets. Other outcomes would have also been reasonable such as the Democrats losing Virginia and the senate remaining in republican hands, a possibility that came very close to happening.

We plan a map with a better design and more features for the 2008 Electoral College and Senate races. Stay tuned.

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Posted by Lance to Computational Complexity at 11/09/2006 10:56:00 AM

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