Champagne corks were popping on Hillary’s campaign plane during the day on election days as exit polls seemed to show that key demographic voters were coming out in big numbers for Clinton.

Mrs. Clinton’s campaign was so confident in her victory that her aides popped open Champagne on the campaign plane early Tuesday. But that conviction, aides would later learn, was based largely on erroneous data showing that young, black and Latino voters and suburban women who had been turned off by Mr. Trump’s comments but viewed Mrs. Clinton unfavorably would turn out for her in higher numbers than they ultimately did.

Exit polls conducted by Edison Research found that among people who said they had decided in the final week before Election Day, 47 percent voted for Mr. Trump and 42 percent for Mrs. Clinton.

As early as Wednesday morning, aides began to explain to Democrats shaken by the loss that the campaign’s sophisticated data modeling had not taken into account the bombshell F.B.I. announcement.

That also begs the question, “Did Hillary not make an appearance because she couldn’t stop crying or because she was too drunk?”