Nate Silver Isn’t An Outlier

Oct 31 2012 @ 11:14am

Obama_Win_Probablity

Ezra Klein defends Nate Silver against criticism:

If Mitt Romney wins on election day, it doesn’t mean Silver’s model was wrong. After all, the model has been fluctuating between giving Romney a 25 percent and 40 percent chance of winning the election. That’s a pretty good chance! If you told me I had a 35 percent chance of winning a million dollars tomorrow, I’d be excited. And if I won the money, I wouldn’t turn around and tell you your information was wrong. I’d still have no evidence I’d ever had anything more than a 35 percent chance.

Jonathan V. Last makes related points:

People seem to think that it would reflect badly on Silver if Romney were to win while Silver’s model shows only a 25 percent chance of victory. But isn’t 25 percent kind of a lot? If I told you there was a 1-in-4 chance of you getting hit by a bus tomorrow, would you think that 25 percent seemed like a big number or a little number? Or, to put it another way, a .250 hitter gets on base once a game, so you’d never look at him in any given at bat and think there was no chance he’d get a hit.

Nyhan provides the above chart:

Silver’s estimates are generally somewhat more conservative than the other statistical forecasting models and only moderately more confident in an Obama victory than the betting markets. Whatever objection pundits or conservatives may have is with the state of the publicly available evidence or the way in which forecasters and bettors translate that evidence into probabilities, not with Silver or his methods.