Trust in Polling
If there's any remaining confusion about what happened with election polling in the 2016 presidential campaign, the Pew Research Center clears it up in this 6-minute video. The key takeaways: while national polls were very accurate, state polls largely missed a late swing to Donald Trump and underrepresented people without college educations.
But there's a larger point here. Election polls make news, but they're not the highest value of opinion research. Polls are matchless in their ability to understand people's values. They explore the "contours of social attitudes," as Pew puts it: values, preferences, priorities and concerns.