No matter where you situate yourself on the political spectrum, don’t try to deny that the 2016 US presidential election made you go “whaaaaaaat?” This isn’t a judgment; if you believe Michael Wolff’s book, even Donald Trump didn’t think Donald Trump was going to be president.
Even if you didn’t spend 2016 frantically refreshing Fivethirtyeight and arguing the relative merits of Sam Wang versus Larry Sabato (no judgment), if you just watched the news, you probably thought that Hillary Clinton had anywhere from a 71 percent to 99 percent chance of becoming president.
Pollsters were “completely and utterly wrong,” it seemed at the time, because of low response rates to telephone polls, which tend to be over landlines, which people tend to not answer anymore.
In fact, if you look at polling from 220 national elections since 1942—that’s 1,339 polls from 32 countries, from the days of face-to-face interviews to today’s online polls—you find that while polls haven’t gotten much better at predicting winners, but they haven’t gotten much worse, either.
“You look at the final week of polls for all these countries, and essentially look at how those change,” says Will Jennings, a political scientist at the University of Southampton and coauthor of a new paper on polling error in Nature Human Behaviour.
As more people start thinking about voting and more polls start polling, the results become more accurate.