Scientific Predictions of US Election

An interesting story from the US, where there are many polls and predictions of who is going to win the 2012 presidential election. There is a prediction on a NY Times blog called FiveThirtyEight, which today gives Obama a 79% chance of winning. This value changes daily.  However I don’t know how this value is reached because the methods are kept secret. According to the blog “FiveThirtyEight provides forecasts of upcoming presidential, Congressional and gubernatorial elections through the use of its proprietary prediction models.”

This blog has been coming in for some criticism on Politico, apparently because it doesn’t take into account the fact that the polls are very close. I can’t understand the logic of the criticism in this article. I think they want the prediction to be 50-50. The author does not seem to understand the concept of probability. The final sentence is, if Obama wins, “you won’t know if he actually had a 50.1 percent chance or a 74.6 percent chance of getting there.”

I quote from the Politico link: Times columnist David Brooks, a moderate conservative, said on PBS earlier this month. “The pollsters tell us what`s happening now. When they start projecting, they`re getting into silly land…. If there’s one thing we know, it’s that even experts with fancy computer models are terrible at predicting human behavior.”

Predictions are made based on certain assumptions using a mathematical formula. The assumptions should be made clear, and then the prediction follows from mathematics. There is nothing to argue about. Well ok, you can argue about whether the assumptions are valid, and you can argue about whether the mathematical formula is correct. But that’s not the point. The point is, that with these assumptions and using this model, you get these predictions. You can’t argue.

There is a staunch defence of the 538 blog at The Atlantic Wire, which has another article here. Ezra Klein writes about it here.

My only criticism is that the 538 methods are secret. So we don’t know how the results are arrived at. It could be scientific, or maybe not, we don’t know.


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