Founded by Nate Silver in 2008, 538 focuses on opinion driven poll analysis, politics, economics, sports, science, and culture. The website gained popularity from its accuracy in predicting U.S. election outcomes.
538’s pollster ratings are calculated by analyzing the historical accuracy and methodological transparency of each polling organization’s polls. 538 define accuracy as the average adjusted error and bias of a pollster’s surveys. Error and bias scores are adjusted for polls’ sample sizes, how far before the election they were conducted, the type of election polled, and the polls’ performance relative to other polls surveying the same race and other factors