By James Kwak
Many people have spilled far more words on this topic than I can read, but I wanted to point out a few things that seem clear to me:
- As Daniel Engber pointed out, the fact that Obama won (and that Silver called all fifty states correctly) doesn’t prove that Silver is a genius any more than Obama’s losing would have proven that he was a fraud.
- In fact, Silver appears to have gotten a couple of Senate races wrong, but that still doesn’t prove anything, since his model spits out probabilities, not certainties.
- To my mind, the crux of the debate was between: (a) people who believe that it is meaningful to make probabilistic statements about the future based on existing data (both current polls and parameters estimated from historical data); and (b) people who believe that there is something ineffable about politics that escapes analysis and that therefore there is something fundamentally wrong, or misleading, or fraudulent about the statistical approach. Silver, through no fault of his own, because associated with (a). To my mind, (a) is right and (b) is wrong because of logic and math, so the idea that one election could have settled the question was crazy to begin with.
- Within camp (a), there are certainly valid methodological debates, and it’s by no means clear that Silver is the state of the art. Whether, in the last days of an election, he is any better than simple averages is an open question. The value Silver adds or doesn’t add can’t be judged by the final forecast, because one point of his model is to incorporate factors that are not incorporated in current polls (e.g., economic conditions). (Another aspect of the model is to not overreact to short-term trends—but that aspect also largely vanishes by the night before.) So the superiority of the model, if it is superior, would appear months before the election, not the night before. But that is even harder to verify by ultimate results. Ideally you would have many elections and for each one you would have a Silver forecast six months before and a simple poll average six months before and you would see which had a higher batting average. I would bet on Silver, but we’ll never have enough data to resolve that question.
If the outcome makes people take statistics more seriously and pundits less seriously, that’s a good thing, but it’s not why you should take statistics more seriously.