Republican Larry Hogan shocked many on Election Day in an upset win over Democrat Anthony G. Brown in the race for governor. Brown, the sitting lieutenant governor, had been favored by pollsters since June's primary election and was able to call on the assistance of Democratic party heavyweights, including Bill Clinton and Michelle Obama. Over time, though, Brown’s lead in the polls shrank from 20 points in a summer Washington Post poll to 7 points in The Sun’s October poll.
Nonetheless, renowned political forecaster Nate Silver of FiveThirtyEight.com gave Brown a 94 percent chance of victory on the eve of the election. As Harry Enten wrote for FiveThirtyEight, "Our forecast wasn’t even close." Given the data FiveThirtyEight.com had, Enten likens the probability of Hogan's nearly five percentage point win over Brown to the odds of No. 14 seed Mercer defeating No. 3 seed Duke in March's NCAA men's basketball tournament. However, Enten notes that his modeling included no poll data after early October.
"Our gubernatorial model relies on polls, and polls alone, and the most reliable public [nonpartisan] pollsters stopped surveying the race a month before Election Day," said Enten.
As a matter of policy, FiveThirtyEight excludes partisan polls to avoid party or campaign bias.
So, how did other pollsters' predictions stack up? Explore the interactive chart below.
Voter turnout, or lack thereof also gave Hogan an edge on Election Day. Registered voter turnout averaged 44.5 percent statewide, and three of the four counties Brown won bottomed out the list of turnout. To explore how counties voted, explore our interactive map.