FiveThirtyEight, also rendered as 538, was an American website that focused on opinion poll analysis, politics, economics, and sports blogging in the United States.
The website, which took its name from the number of electors in the United States electoral college, was founded on March 7, 2008, as a polling aggregation website with a blog created by analyst Nate Silver. In August 2010, the blog became a licensed feature of The New York Times online and was renamed FiveThirtyEight: Nate Silver's Political Calculus. In July 2013, ESPN acquired FiveThirtyEight, hiring Silver as editor-in-chief and a contributor for ESPN.com; the new publication launched on March 17, 2014. Afterwards, the FiveThirtyEight blog covered a broad spectrum of subjects including politics, sports, science, economics, and popular culture. In 2018, operations were transferred from ESPN to sister property ABC News (also under parent The Walt Disney Company).
During the presidential primaries and general election of 2008 the site compiled polling data through a unique methodology derived from Silver's experience in sabermetrics to "balance out the polls with comparative demographic data".Andrew Romano (June 16, 2008). "Making His Pitches: Nate Silver, an all-star in the world of baseball stats, may be the political arena's next big draw". Newsweek. Silver weighted "each poll based on the pollster's historical track record, sample size, and recentness of the poll". Since the 2008 election, the site published articles—typically creating or analyzing statistical information—on a wide variety of topics in current politics and political news. These included a monthly update on the prospects for turnover in the Senate; federal economic policies; Congressional support for legislation; public support for health care reform, global warming legislation and LGBT rights; elections around the world; marijuana legalization; and numerous other topics. The site (as well as its founder) was best known for election forecasts, including the 2012 presidential election in which FiveThirtyEight correctly predicted the vote winner of all 50 states and the District of Columbia.
FiveThirtyEight won numerous awards, including Bloggie Awards for Best Political Coverage in 2008 and Best Weblog about Politics in 2009 as well as Webbies for Best Political Blog in 2012 and 2013. While under the ownership of ESPN in 2016, FiveThirtyEight won the Data Journalism Website of the Year award from the Global Editors Network.
Founder Nate Silver left in 2023, taking the rights to his forecasting model with him to his website Silver Bulletin. The site's new owner, Disney, hired G. Elliott Morris to develop a new model. On September 18, 2023, the original website domain at fivethirtyeight.com was closed, with web traffic becoming redirected to ABC News pages, and its logo was replaced, with the name 538 used instead of FiveThirtyEight. On March 5, 2025, 538 was shut down by ABC News and its staff were laid off. On May 15, 2026, ABC redirected thousands of archived 538 articles to the politics section of their news website, making them inaccessible.
Methods One aspect of the site was 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. Silver said: "I did think there was room for a more sophisticated way of handling these things."
FiveThirtyEight weighted pollsters' historical track records through a complex methodology, and assigned them values to indicate "Pollster-Introduced Error". At its 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 neither reveal the true state of 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.
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 on 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.
Transparency of pollster ratings On June 6, 2010, FiveThirtyEight posted pollster rankings that updated and elaborated Silver's efforts from the 2008 election. Silver expanded the database to more than 4,700 election polls and developed a model for rating the polls that was more sophisticated than his original rankings. Silver responded on 538: "Where's the transparency? Well, it's here [citing his June 6 article], in an article that contains 4,807 words and 18 footnotes. Every detail of how the pollster ratings are calculated is explained. It's also here [referring to another article], in the form of Pollster Scorecards, a feature which we'll continue to roll out over the coming weeks for each of the major polling firms, and which will explain in some detail how we arrive at the particular rating that we did for each one".
As for why the complete 538 polling database had not been released publicly, Silver responded: "The principal reason is because I don't know that I'm legally entitled to do so. The polling database was compiled from approximately eight or ten distinct data sources, which were disclosed in a comment which I posted shortly after the pollster ratings were released, and which are detailed again at the end of this article. These include some subscription services, and others from websites that are direct competitors of this one. Although polls contained in these databases are ultimately a matter of the public record and clearly we feel as though we have every right to use them for research purposes, I don't know what rights we might have to re-publish their data in full." Silver also commented on the fact that the 538 ratings had contributed to Markos Moulitsas's decision to end Daily Kos use of Research 2000 as its pollster.
On June 11, 2010, Mark Blumenthal also commented on the question of transparency in an article in the National Journal titled "Transparency In Rating: Nate Silver's Impressive Ranking Of Pollsters' Accuracy Is Less Impressive In Making Clear What Data Is Used". He noted that in the case of Research 2000 there were some discrepancies between what Silver reported and what the pollster itself reported. Other researchers questioned aspects of the methodology.
On June 16, 2010, Silver announced on his blog that he is willing to give all pollsters who he had included in his rating a list of their polls that he had in his archive, along with the key information that he used (poll marginals, sample size, dates of administration); and he encouraged the pollsters to examine the lists and the results to compare them with the pollster's own record and make corrections.
In September 2014, Silver put into the public domain all of his pollster ratings, as well as descriptive summary data for all of the more than 6,600 polls in his data collection for the final three weeks of U.S. presidential primaries and general elections, state governor elections, and U.S. Senate and U.S. Congress elections for the years 1998–2012. In addition to updating his pollster ratings, he published an updated methodological report.
History Origins
Nate Silver started FiveThirtyEight in early March 2008, published under the pseudonym Poblano, the same name that he had used since November 2007 when he began publishing a diary on the political blog Daily Kos. The name FiveThirtyEight derives from the 538 electors in the United States Electoral College. Writing for Daily Kos, Silver 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 final contests, Obama won 847 delegates and Clinton 834. Based on this result, New York Times op-ed columnist William Kristol wrote: "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".
FiveThirtyEight 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 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. On May 30, 2008, Silver revealed his true identity for the first time to his FiveThirtyEight readers. After that date, he published just four more diaries on Daily Kos.
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. In 2008, Rasmussen Reports had an apparently short-term partnership with FiveThirtyEight in order to include this unique methodology for generating poll averages in their "Balance of Power Calculator". At the same time, FiveThirtyEights daily "Today's Polls" column began to be mirrored on "The Plank", a blog published by The New Republic.
In July 2008, the site began to report regular updates of 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.