Nate Silver’s Flawed Model
The New York Times number cruncher lets his partisanship show.

Statistician Nate Silver



In that same post, Silver touts a “SurveyUSA poll showing Mr. Obama with a one-point lead in Florida is really the slightly better result for him.” That SurveyUSA poll indeed had Obama up by one point, but had a Democratic party-ID advantage of nine points. In 2008 Democrats had a three-point advantage, and in 2010 the parties were even. So the SurveyUSA poll is good news only if you believe Democrats will not only improve on their 2008 turnout, but triple their turnout advantage over Republicans.


This is the type of analysis that walks a very thin line between forecasting and cheerleading. When you weight a poll based on what you think of the pollster and the results and not based on what is actually inside the poll (party sampling, changes in favorability, job approval, etc), it can make for forecasts that mirror what you hope will happen rather than what’s most likely to happen. This is also true of Silver’s dismissal of Romney’s lead in Gallup this week. While Romney is likely not up by seven points nationally, as the poll predicted, you can’t dismiss it while at the same time giving a twelve-day-old Marist/NBC Ohio poll a higher weighting than eight newer polls when Marist has leaned Obama this entire cycle.

All of this also completely ignores the fact that it is more important for Obama to cross the 50 percent threshold in national polls before Election Day than it is for Romney. While it’s impossible to know how the late deciders will break, the historical trend has been for them to break for the challenger. If the Real Clear Politics average is tied at 47 percent, the overwhelming odds are that the last 6 percent will break heavily to Romney. While that would not guarantee an Electoral College victory, it is very difficult to imagine a scenario where Romney wins the national vote by more than a percentage point and loses the Electoral College.

On November 7, after the dust settles from Election Day and we (hopefully) have a winner, it might very well turn out that Nate Silver once again successfully predicted the battleground states and thus the election. But midway through October, 2012 is shaping up to be a far different election than the one in which Silver made his name. One must wonder if Silver’s forecast model includes a little bit too much hope of an Obama victory against what appears to be a surge of Romney momentum. Obama’s aura of inevitability is quickly losing steam, and once that runs out, even Homer Simpson will have a hard time proving otherwise.

— Josh Jordan is a small-business market-research consultant. You can follow him on Twitter @Numbersmuncher.