FiveThirtyEight

FiveThirtyEight

File:Fivethirtyeightlogo.png
Type of site	Opinion poll analysis, blog
Available in	English
Owner	Nate Silver
Created by	Nate Silver
URL	www.fivethirtyeight.com
Commercial	Yes
Registration	Optional

FiveThirtyEight.com, named after the number of electors in the United States electoral college, is a liberal leaning political website established in March 2008 by Nate Silver. The site compiles polling data through a unique methodology derived from Silver's experience in baseball sabermetrics to "balance out the polls with comparative demographic data" and "weighting each poll based on the pollster's historical track record, sample size, and recentness of the poll."

For the 2008 Presidential Election, FiveThirtyEight.com also used computer models to simulate the election 10,000 times per day in order to provide a continually up-to-date assessment of probability for electoral outcomes.

History

When Silver started FiveThirtyEight.com he published under the name "Poblano," the same name that he had used when publishing a diary on the political blog Daily Kos since November 2007. Writing as Poblano on Daily Kos, he had gained a following especially for his primary election forecast on Super Tuesday, February 5, 2008. From that primary election day, which included contests in 24 states plus American Samoa, "Poblano" predicted that Barack Obama would come away with 859 delegates, and Hillary Clinton 829; in the actual contests, Obama won 847 delegates and Clinton 834. Based on this result, New York Times op-ed columnist William Kristol cited "Poblano" thus: "And an interesting regression analysis at the Daily Kos Web site (poblano.dailykos.com) of the determinants of the Democratic vote so far, applied to the demographics of the Ohio electorate, suggests that Obama has a better chance than is generally realized in Ohio".

When Silver began FiveThirtyEight.com in early March, 2008, he continued to cross-post most of his columns as "Poblano" on Daily Kos. On May 30, 2008, Silver revealed his true identity for the first time to his FiveThirtyEight.com readers. After that date, he published just three more diaries on Daily Kos.

FiveThirtyEight.com gained further national attention for beating out most pollsters' projections in the North Carolina and Indiana Democratic party primaries on May 6, 2008. As Mark Blumenthal wrote in the National Journal, “Over the last week, an anonymous blogger who writes under the pseudonym Poblano did something bold on his blog, FiveThirtyEight.com. He posted predictions for the upcoming primaries based not on polling data, but on a statistical model driven mostly by demographic and past vote data…. Critics scoffed. Most of the public polls pointed to a close race in North Carolina…. But a funny thing happened. The model got it right.” Silver relied on demographic data and on the history of voting in other states during the 2008 Democratic primary elections. “I think it is interesting and, in a lot of ways, I’m not surprised that his predictions came closer to the result than the pollsters did,” said Brian F. Schaffner, research director of American University’s Center for Congressional and Presidential Studies.

As the primary season was coming to an end, Silver began to build a model for the general election race. This model, too, relied in part on demographic information but mainly involved a complex method of aggregating polling results. On June 13, Rasmussen Reports began partnering with FiveThirtyEight.com in order to include this unique methodology for generating poll averages in their "Balance of Power Calculator". At the same time, FiveThirtyEight.com's daily "Today's Polls" column began to be mirrored on "The Plank," a blog published by The New Republic.

By June 25, entering "FiveThirtyEight" in a Google search generated a list of more than 150,000 articles that mentioned FiveThirtyEight.com; by October 13 the same search yielded more than 400,000 articles; by November 5, more than 580,000; by December 29, after the excitement of the election had died down, this search still yielded 480,000 articles. By early October, FiveThirtyEight.com approached 2.5 million visitors per week, while averaging approximately 400,000 per weekday. During October 2008 the site received 3.63 million unique visitors, 20.57 million site visits, and 32.18 million page views. On Election Day, November 4, 2008, the site had nearly 5 million page views.

Methods of electoral forecasts, 2008

Weighting of polls

One unique aspect of the site is Silver’s efforts to rank pollsters by accuracy, weight their polls accordingly, and then supplement those polls with his own electoral projections based on demographics and prior voting patterns. “I did think there was room for a more sophisticated way of handling these things,” Silver said.

FiveThirtyEight.com weighs pollster's historical track record through a complex methodology and assigns them a value to indicate "Pollster-Introduced Error (PIE)".

Polls on FiveThirtyEight.com are weighted using a half-life of thirty days using the formula 0.5^P/30 where 'P' is the number of days transpired since the median date that the poll was in the field. The formula is based on an analysis of 2000, 2004, and 2006 state-by-state polling data.

Smoothing the poll results

At base Silver's method is similar to other analysts' approaches to taking advantage of the multiple polls that are conducted within each state: he averaged the polling results. But especially in the early months of the election season polling in many states is sparse and episodic. The "average" of polls over an extended period (perhaps several weeks) would not reveal the true trend in voter preferences at the present time, nor provide an accurate forecast of the future. One approach to this problem was followed by Pollster.com: if enough polls were available, it computed a locally weighted moving average or LOESS.

However, while adopting such an approach in his own analysis, Silver reasoned that there was additional information available in polls from "similar" states that might help to fill the gaps in information about the trends in a given state. Accordingly, he adapted an approach that he had previously used in his baseball forecasting: using nearest neighbor analysis he first identified "most similar states" and then factored into his electoral projections for a given state the polling information from "similar states." He carried this approach one step further by also factoring national polling trends into the estimates for a given state. Thus, his projections were not simply based on the polling trends in a given state.

Furthermore, a basic intuition that Silver drew from his analysis of the 2008 Democratic party primary elections was that the voting history of a state or Congressional district provided clues to current voting. This is what allowed him to beat all the pollsters in his forecasts in the Democratic primaries in North Carolina and Indiana, for example. Using such information allowed Silver to come up with estimates of the vote preferences even in states for which there were few if any polls. For his general election projections for each state, in addition to relying in the available polls in a given state and "similar states," Silver estimated a "538 regression" using historical voting information along with demographic characteristics of the states to create an estimate that he treated as a separate poll (equivalent to the actually available polls from that state). This approach helped to stabilize his projections, because if there were few if any polls in a given state, the state forecast was largely determined by the 538 regression estimate.

Additional aspects of the methodology are described in a detailed FAQ on the FiveThirtyEight.com website.

Senate races

In July 2008, the site began to report projections of 2008 U.S. Senate races. Special procedures were developed relying on both polls and demographic analysis. The projections were updated on a weekly basis.

Swing state analysis

The site presents an analysis of the swing states, focusing on so-called "Tipping Point States." 'Tipping Point States' are those states that tip the outcome of the election from one candidate to the other. In each simulation run, the winner's states won are lined up in reverse order of victory margin by percentage. A simple algorithm selects the minimum closest states that, if switched to the loser's side, would change the election outcome, then weights that run's significance based on the margin of victory in the popular vote. Thus, the closer the popular vote, the fewer the number of tipping point states and the greater the significance of that run in assessing tipping point importance. For example, the 2004 election's sole tipping point state was Ohio by this method, while 1960's were Illinois, Missouri, and New Jersey -- even though Hawaii was the closest state race.

Final projections of 2008 election outcome

In the final update of his presidential forecast model at midday of November 4, 2008, Silver projected a popular vote victory by 6.1 percentage points for Barack Obama and electoral vote totals of 349 (based on a probabalistic projection) or 353 (based on fixed projections of each state). Silver's predictions matched the actual results everywhere except in Indiana and the 2nd congressional district of Nebraska, which awards an electoral vote separately from the rest of the state. His projected national popular vote differential was close to the actual figure of 7.2 points.

The forecasts for the Senate proved to be correct for every race that has been settled. But the near stalemate in Minnesota led to a recount that had not been settled as of January 25, 2009. In Alaska, however, after a protracted counting of ballots, on November 19 Republican incumbent Ted Stevens conceded the seat to Democrat Mark Begich, an outcome that Silver had forecast on election day. And in Georgia, a run-off election on December 2 led to the re-election of Republican Saxby Chambliss, a result that was also consistent with Silver's original projection.

The ground game and "On the Road"

A second writer on the site is Sean Quinn. During the 2008 electoral campaign, Quinn drew on his knowledge and experience with campaign organizations to evaluate the ground game and "get out the vote" strategies of the McCain and Obama campaign teams. A poker player, Quinn drew an analogy between Barack Obama's electoral strategy and a poker player having multiple "outs" for winning a hand.

In September, Quinn launched a series of "On the Road" essays, enhanced with photos by photographer-film maker Brett Marty. Quinn and Marty traveled from state to state telling the story of the campaign from the electoral battleground -- drawing on observations and interviews with grassroots campaign workers.

FiveThirtyEight after the 2008 election

During the first two months after the election, no major innovations in content were introduced. A substantial percentage of the articles focused on Senatorial races: the runoff in Georgia, won by Saxby Chambliss; recounts of votes in Alaska (won by Mark Begich), and Minnesota (Al Franken vs. Norm Coleman); and the appointments of Senatorial replacements in Colorado, New York, and Illinois.

During this time, Silver also devoted attention to developing some tools for the analysis of forthcoming Congressional elections, as well as discussing policy issues and the policy agenda for the Obama administration, especially economic policies. He also provided assessments of the likely 2010 Senate races with an eye toward making forecasts of likely party turnover.

Sean Quinn has reported that he is moving to Washington, D.C., and intends to continue political writing from that locale.

Recognition

• In September 2008, FiveThirtyEight became the first blog ever selected as a Notable Narrative by the Nieman Foundation for Journalism at Harvard University. According to the Foundation, "In his posts, former economic analyst and baseball-stats wunderkind Nate Silver explains the presidential race, using the dramatic tension inherent in the run-up to Election Day to drive his narrative. Come November 5, we will have a winner and a loser, but in the meantime, Silver spins his story from the myriad polls that confound us lesser mortals."

• The New York Times described FiveThirtyEight.com in November 2008 as "one of the breakout online stars of the year".

• Huffington Post columnist Jason Linkins named FiveThirtyEight.com as No. 1 of "Ten Things that Managed to Not Suck in 2008, Media Edition."

• FiveThirtyEight.com is the 2008 Weblog Award Winner for "Best Political Coverage".

See also

• Statewide opinion polling for the United States presidential election, 2008
• Electoral College (United States)

External links

• FiveThirtyEight.com
• Nate Silver interview on Bloggingheads.tv