Nate Silver arrives at his new NYT home.

[jefferson_dem]

August 25, 2010, 11:25 am
Welcome (and Welcome Back) to FiveThirtyEight
By NATE SILVER

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Instead, there seems to be something about politics that can make the rational parts of the brain turn off. FiveThirtyEight was designed to be the antidote to that. For readers just becoming acquainted with FiveThirtyEight, the blog is devoted to the rational analysis of politics, and sometimes other data-rich subjects. In Congressional and presidential elections — for which there is a lot of high-quality data available — this will sometimes take the form of quite explicit forecasts, like Harry Reid having a 42 percent chance of keeping his seat in Nevada (hypothetically) or the Republicans having a 20 percent chance of winning the Senate (again, hypothetically). In other cases, it simply means trying to prioritize objective information over subjective information in dealing with issues in the news.

Although objective and statistical are not quite synonymous, for the most part this approach means that we focus on the numbers, while not losing sight of their context. And it is important to do so in the right way: namely, to use guidance from past elections to inform our understanding of the present.

FiveThirtyEight’s forecasts performed quite well in 2008, predicting 49 of 50 states correctly in the presidential election, as well as all 35 Senate races. Nevertheless, I have re-engineered our Senate model to improve it. It is now much smarter, for instance, in how it estimates the amount of error associated with each forecast. The more the polling tends to diverge in a given race, or the more undecided voters there are, the less confident it is in its projections.

Our new House forecasting model, meanwhile, which we plan to release next week, uses a multiplicity of indicators (national and local polls, forecasts from experts like Cook Political, fund-raising data, and so forth) to project the outcome of each seat, a calibration that is based on the amount of predictive power that each indicator has had in the past. Although polling is a key input in each of our models, we do not use it verbatim: we adjust our analysis to account for polls that show a consistent partisan bias, for instance, and give more weight to polls that have been more accurate in the past.

This approach — not just objective and statistical, but rigorous and empirical — is especially prudent when it comes to evaluating the upcoming midterm elections. The Democrats will almost certainly lose seats in both houses of Congress, but exactly how many is an open question. A casual reading of trends is somewhat unhelpful: Americans are very unhappy with the direction of the country and, increasingly, with President Obama. But in contrast to 1994, the Republicans’ favorability ratings are also near their all-time lows. Meanwhile, looking at a single statistical indicator does not provide for precision, and some indicators disagree with one another. It is perhaps necessary to dig a bit deeper — to look at more data, and to do so in a more robust way — in order to have a truly good handle on how things are likely to proceed. And even then there can still be a lot of uncertainty in the forecast. FiveThirtyEight and its statistical models are willing to admit what they don’t know.

Of course, this is now all going to be done under the auspices of a mainstream media partner: The New York Times, which is not only hosting the blog but is enlisting its team of interactive journalists and graphics experts to deepen and enhance it. While I hope this move broadens FiveThirtyEight’s audience, I welcome to the new venue the many loyal readers who have followed the blog over the past two and a half years.

Fundamentally, I’ve always seen FiveThirtyEight’s mission as being parallel to journalism: objectivity and accuracy have been core values of the blog, but it has also prized clarity of thought and of written and visual communication. Therefore, this is a pretty natural partnership. But I also recognize that this will lead to greater criticism and scrutiny. For the most part, we welcome it: many of the biggest improvements to FiveThirtyEight’s forecasting products have come in response to points raised by our critics, and the blog would never have existed in the first place if I had been more satisfied with the way the press covers politics. We hope to hear frequently from our readers, and we hope that you’ll join us from now until November and in the months and years ahead.

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http://fivethirtyeight.blogs.nytimes.com/

[zipplewrath]

1. I wish him well

He does have a rigorous approach. The 2008 was probably easier to predict because the spreads were alway so large and the uncertainty declined as it approached November. He may find 2010 to be a bit larger in uncertainty which will make it harder to call individual races. 2 or 3 races, either way, in the senate is going to pretty much define this election season, unless something drastic happens in the House.

[Yavin4]

2. He Predicted That This Would Happen

+/- a few points.