One of the most respected and accurate forecasting models in political sciences says that Donald Trump will win the 2016 presidential election, and by a fairly comfortable margin at that. There's just one problem: Its creator doesn't believe his own forecast. Emory political scientist Alan Abramowitz's "Time for Change" makes predictions by considering how the economy is doing (measured by the GDP growth rate the second quarter of the election year), how popular the incumbent is (measured by his Gallup approval rating at the end of June), and whether the incumbent is running for reelection. It has correctly predicted every...