Here’s the best defense yet of polling analyst Nate Silver
[Note: I’m writing this as a free-standing post rather than including it in our Daily Poll Watch, which will be largely devoted later today to the latest numbers in the presidential race.]
In a post HERE the other day, I dealt with the rising tide of right-wing criticism of celebrated polling analyst Nate Silver [above], who writes for The New York Times.
The disparagement of Silver has since continued apace, prompting Ezra Klein of The Washington Post to respond with THIS PIECE. You should read the whole thing, and here a few excerpts to whet your appetite:
As of this writing, Silver thinks Obama has a 75 percent chance of winning the election…Moreover, Silver’s model is currently estimating that Obama will win 295 electoral votes. That’s eight fewer than predicted by Sam Wang’s state polling meta-analysis and 37 fewer than Drew Linzer’s Votamatic…
Every major political betting market and every major forecasting tool is predicting an Obama victory right now, and for the same reason: Obama remains ahead in enough states that, unless the polls are systematically wrong, or they undergo a change unlike any we’ve yet seen in the race, Obama will win the election.
It’s important to be clear about this: If Silver’s model is hugely wrong — if all the models are hugely wrong, and the betting markets are hugely wrong — it’s because the polls are wrong. Silver’s model is, at this point, little more than a sophisticated form of poll aggregation.
But it’s just as important to be clear about this: 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.
There are good criticisms to make of Silver’s model…[b]ut the good arguments over Silver’s model are being overwhelmed by very bad ones.
First, there are the conservatives who don’t like Silver’s model because, well, they don’t like it. Obama’s continued strong showing is prima facie evidence of bias. Or, to put it slightly differently, the model must be skewed.
The answer to this is simple enough: If Silver’s model is systematically biased, there’s a market opportunity for anyone who wants to build a better model…
Then there’s the backlash from more traditional media figures…Silver’s work poses a threat to more traditional — and, in particular, to more excitable — forms of political punditry and horse-race journalism.
If you had to distill the work of a political pundit down to a single question, you’d have to pick the perennial “who will win the election?” …Now Silver — and Silver’s imitators and political scientists — are taking that question away from us. It would be shocking if the profession didn’t try and defend itself.
[E]lection forecasters have better incentives than homepage editors. For instance, note that all these attacks on Silver take, as their starting point, Silver’s continuously updated prediction for the presidential election, which includes point estimates for the popular vote and electoral college, and his predictions for the Senate races. Those predictions let readers check Silver’s track record and they force Silver, if he wants to keep his readers’ trust, to make his model as accurate as he can. That’s a good incentive structure — certainly a better one than much of the rest of the media has — and my guess is his results, over time, will prove it.