… Trump’s Election Day victory, with 306 electoral votes, took us by surprise. My forecast was wrong. It’s time to understand why.
The forecast was based on a statistical model that analyzed nearly 1,400 state-level pre-election public opinion polls, in combination with a set of political and economic “fundamentals” that added information about the election’s historical context. The fundamental factors (which turned out to predict the national vote share very closely) indicated that Clinton faced an uphill climb from the very beginning. In May, I estimated that Clinton’s baseline probability of victory was around 35 percent.
But all summer long, right up to Election Day, the polls told a different story. CONT.
Drew Linzer, Daily Kos