What went wrong with last year’s election surveys?

You’d be forgiven for thinking there isn’t anything left to say on this topic, but the American Association for Public Opinion Research (AAPOR) convened a task force to explore what went wrong with the state polls that missed the mark (national polls weren’t too far off). It found two notable problems: (1) that undecided voters broke late and almost uniformly for Trump, and (2) Americans with less education were underrepresented in the polls.