Nate Silver explains the math the haters ignore

nate-silver-at-nyt-desk.jpgSure, the writer and stats guru behind the New York Times' FiveThirtyEight blog has a complex algorithm to back up saying that President Obama is the favorite to win on Tuesday. But the math, he says, is actually quite simple: "Obama’s ahead in Ohio."

Silver explains on the blog:

A somewhat-more-complicated version:


Mr. Obama is leading in the polls of Ohio and other states that would suffice for him to win 270 electoral votes, and by a margin that has historically translated into victory a fairly high percentage of the time.

The argument that Mr. Obama isn’t the favorite is the one that requires more finesse. If you take the polls at face value, then the popular vote might be a tossup, but the Electoral College favors Mr. Obama.

So you have to make some case for why the polls shouldn’t be taken at face value.

Some argue that the polls are systematically biased against Republicans. This might qualify as a simple argument had it been true on a consistent basis historically, but it hasn’t been: instead, there have been some years when the polls overestimated how well the Democrat would do, and about as many where the same was true for the Republican. I’m sympathetic to the notion that the polls could be biased, statistically speaking, meaning that they will all miss in the same direction. The FiveThirtyEight forecast explicitly accounts for the possibility that the polls are biased toward Mr. Obama — but it also accounts for the chance that the polls could be systematically biased against him.

Others argue that undecided voters tend to break against the incumbent, in this case Mr. Obama. But this has also not really been true in recent elections. In some states, also, Mr. Obama is at 50 percent of the vote in the polling average, or close to it, meaning that he wouldn’t need very many undecided voters to win.

A third argument is that Mr. Romney has the momentum in the polls: whether or not he would win an election today, the argument goes, he is on a favorable trajectory that will allow him to win on Tuesday.

This may be the worst of the arguments, in my view. It is contradicted by the evidence, simply put.

Silver is kind to say there has been "pushback" against his conclusion. Actually, he's being fairly aggressively demonized by the media activists on the right. For the moment, it appears the mini-brouhaha over his challenge to MSNBC's Joe Scarborough has run out of steam. If you missed it, Morning Joe alleged Silver's numbers were bogus, so Silver basically bet him $1,000 that Obama would win, with the money going to charity. The NYT's Public Editor, a job in which the incumbent is supposed to scold the Times for various misdeeds to make critics happy, called the bet challenge unseemly. But media commentators have rushed to Silver's defense.

If Obama wins the demonizing of Silver probably goes away. If Romney wins, it will look to many as if Silver was off base. But he doesn't claim evidence, based on others'
polling and his analysis of previous events, that Obama is sure to win. Just that it appears the more likely outcome, based on the available data.

Photo of Silver at his New York Times desk. Stephanie Strom via Jim Romenesko


More by Kevin Roderick:
Tonight, we share some love with Brooklyn
Nate Silver explains the math the haters ignore
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