If you’ve ever gone on Nate Silver’s 538 Blog for The New York Times, you’ll see where reality ends, and fantasy begins. It was more vividly displayed after the third and last presidential debate where I wrote, in a previous post, for Hot Air that “the headline for his [Silver’s] October 23 post after the last presidential debate read ‘Obama unlikely to get big debate bounce, but a small one could matter.” Talk about grasping at straws.
Still, with the contest being so tight, any potential gain for Mr. Obama could matter. Mr. Obama was roughly a 70 percent Electoral College favorite in the FiveThirtyEight forecast in advance of the debate, largely because he has remained slightly ahead in polls of the most important swing states.
If Mr. Obama’s head-to-head polling were 2 percentage points higher right now, he would be a considerably clearer favorite in the forecast, about 85 percent. A 1-point bounce would bring him to 80 percent, and even a half-point bounce would advance his position to being a 75 percent favorite in the forecast.
Still, Mr. Obama should not take even that for granted. There have been some past debates when the instant-reaction polls judged one candidate to be the winner, but the head-to-head polls eventually moved in the opposite direction.
So, since Obama is ahead of Romney within the margin of error, why does that constitutes a win for the president? I think most analysts would put a 2-4 point lead, for any candidate, in the toss-up column – especially for a battleground state. Thus, making his 70% prediction of an Obama victory a nonsensical exercise. Silver has states listed as toss-ups on the blog, but didn’t reference them here.
Furthermore, Silver’s notion that a half point ounce would increase Obama’s probability of re-election to 75%, a 1 point bounce to 80%, and a 2 point bounce to 85% is abjectly senseless. He is lying and waiting for a miracle to happen.
Here in New York, Silver is very much on the tongue of the media and the left-leaning professional elite: Everyone from photographers to the managing partner of a major law firm cops to hitting refresh every hour to stay sane. And out in the Democratic hinterlands, the reaction is much the same.
“I was at a Halloween party last night and it was just kind of funny because we’re down here in South Carolina and none of these people are media people or DC kind of types,” said Teresa Kopec, a substitute teacher from Spartanburg, South Carolina. “And they were kind of whispering to each other, ‘But Nate Silver says…’”
“If people have heard of him down here in South Carolina that’s kind of amazing,” Kopec said.
Furthermore, Gray noted that “some Democrats, meanwhile, concede that their affection for the wonky analyst is less the details of his model than the consistency of his message.” That being Obama wins – in every projection he runs.
With Silver catching flak it wasn’t long before his allies at The Washington Post, namely Ezra Klein, decided to jump in front of the train for his liberal colleague. “Before we get too deep in the weeds here, it’s worth being clear about exactly what Silver’s model — and that’s all it is, a model — is showing. As of this writing, Silver thinks Obama has a 75 percent chance of winning the election. That might seem a bit high, but note that the BetFair markets give him a 67.8 percent chance, the InTrade markets give him a 61.7 percent chance and the Iowa Electronic Markets give him a 61.8 percent chance. And we know from past research that political betting markets are biased toward believing elections are more volatile in their final weeks than they actually are. So Silver’s estimate doesn’t sound so off,” says Klein in his October 30 post on the WonkBlog.
Klein then goes on to trivialize the whole matter by saying:
…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, not the least of which is that, while Silver is almost tediously detailed about what’s going on in the model, he won’t give out the code, and without the code, we can’t say with certainty how the model works. But the model is, at this point, Silver’s livelihood, and so it’s somewhat absurd to assume he’d hand it out to anyone who asks
Here’s the catch. We know his code. In fact, anyone of us can replicate Silver’s methodology on Microsoft Office. As Sean A. Davis, COO of Media Trackers, wrote in The Daily Caller on November 1:
Silver’s key insight was that if you used a simple simulation method known as Monte Carlo, you could take a poll’s topline numbers and its margin of error and come up with a probability forecast based on the poll. The effect of this method was to show that a 50-49 lead in a poll with 1,000 respondents wasn’t really a dead heat at all — in fact, the candidate with 50% would be expected to win two-thirds of the time if the poll’s sample accurately reflected the true voting population.
To a political world unfamiliar with mathematical methods that are normally taught in an introductory statistics course, Silver’s prophecy was nothing short of miraculous.
But was it? To find out, I spent a few hours re-building Nate Silver’s basic Monte Carlo poll simulation model from the ground up. It is a simplified version, lacking fancy pollster weights and economic assumptions and state-by-state covariance factors, but it contains the same foundation of state poll data that supports Nate Silver’s famous FiveThirtyEight model. That is, they are both built upon the same assumption that state polls, on average, are correct.
After running the simulation every day for several weeks, I noticed something odd: the winning probabilities it produced for Obama and Romney were nearly identical to those reported by FiveThirtyEight. Day after day, night after night. For example, based on the polls included in RealClearPolitics’ various state averages as of Tuesday night, the Sean Davis model suggested that Obama had a 73.0% chance of winning the Electoral College. In contrast, Silver’s FiveThirtyEight model as of Tuesday night forecast that Obama had a 77.4% chance of winning the Electoral College.
So what gives? If it’s possible to recreate Silver’s model using just Microsoft Excel, a cheap Monte Carlo plug-in, and poll results that are widely available, then what real predictive value does Silver’s model have?
That’s a very good question. In the meantime, this is Silver’s Electoral College and Election forecasts, which were updated at 7pm on November 4. Immerse yourself in the ignorant – or delusional – bliss.