Why did some polls show a tight race when Sherrill won handily?

Democrat Mikie Sherrill scored a roughly 13-point victory Nov. 4 over her opponent for governor, Republican Jack Ciattarelli — a result that bucked many of the polls that gave Sherrill a single-digit lead over Ciattarelli heading into election day.

One poll had Ciattarelli and Sherrill in a dead heat, according to an Oct. 31 projection by AtlasIntel, considered the "most accurate" poll by statistician Nate Silver, founder of FiveThirtyEight. A poll by Emerson College also had the two in a dead heat at 43%.

Yet she won nearly 1.8 million votes according to the Associated Press, compared to nearly 1.4 million votes for Ciattarelli.

And the turnout was closer to 50% than the expected 40%, said Patrick Murray, a political consultant who previously led the Monmouth University Polling Ins