“I think that when it comes to Donald Trump, the interpretation here is probably that pollsters did what they should do scientifically, which is to say make our best prediction based on last time,” says Pasek, assistant professor of communication studies at the University of Michigan. “But the parameters on the ground were fundamentally different in that the kinds of people who voted this time were not a mirror of who voted last time. … Models underestimated the likelihood of turnout that poured from the relatively less-educated (who typically vote less often) white Republicans.”

Read more at Scientific American.