Sorry Republicans, Polls Don’t Have Partisan Bias

Republican pundits this election season have been prattling on about how all the polls showing Obama to be ahead of Mitt Romney, aren’t true selections of the electorate. They say the polls are biased, and that the race is really much closer. Nate Silver, of the New York Times’ FiveThirtyEight blog, begs to differ. He’s compiled a list of polling data, election data, and post-election polls to see if polls have a naturally partisan bias. The answer? A resounding “no.”

Here’s an excerpt from his wonderful piece:

In 2004, Democratic Web sites were convinced that the polls were biased toward George W. Bush, asserting that they showed an implausible gain in the number of voters identifying as Republicans. But in fact, the polls were very near the actual result. Mr. Bush defeated John Kerry by 2.5 percentage points, close to (in fact just slightly better than) the 1- or 2-point lead that he had on average in the final polls. Exit polls that year found an equal number of voters describing themselves as Democrats and Republicans, also close to what the polls had predicted.

Since President Obama gained ground in the polls after the Democrats’ convention, it has been the Republicans’ turn to make the same accusations. Some have said that the polls are “oversampling” Democrats and producing results that are biased in Mr. Obama’s favor. One Web site,unskewedpolls.com, contends that even Fox News is part of the racket in what it says is a “trend of skewed polls that oversample Democratic voters to produce results favorable for the president.”


The criticisms are largely unsound, especially when couched in terms like “oversampling,” which implies that pollsters are deliberately rigging their samples.

But pollsters, at least if they are following the industry’s standard guidelines, do not choose how many Democrats, Republicans or independent voters to put into their samples — any more than they choose the number of voters for Mr. Obama or Mitt Romney. Instead, this is determined by the responses of the voters that they reach after calling random numbers from telephone directories or registered voter lists.

The polls have no such history of partisan bias, at least not on a consistent basis. There have been years, like 1980 and 1994, when the polls did underestimate the standing of Republicans. But there have been others, like 2000 and 2006, when they underestimated the standing of Democrats.

Here’s an image representing the data, also courtesy of Silver’s article:

While I certainly enjoy traffic on my own articles, I must recommend that you go read his article in its entirety. It contains a lot of extremely relevant and interesting information that I can’t list here without overstepping ethical boundaries regarding another journalist’s work.

Current data suggests, using Nate Silver’s “political calculus,” that President Obama has an 83.8% chance of winning the election this election season, with a current estimated 319.3 electoral vote count.

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