Groupthink produced a failure of the “wisdom of crowds” and an underestimate of Trump’s chances.

By Nate Silver

Filed under The Real Story Of 2016

Published Mar. 10, 2017

This is the ninth article in a series that reviews news coverage of the 2016 general election, explores how Donald Trump won and why his chances were underrated by most of the American media.

Last summer, the United Kingdom voted to leave the European Union in what bettors, financial markets and the London-based media regarded as a colossal upset. Reporters and pundits were quick to blame the polls for the unexpected result. But the polls had been fine, more or less: In the closing days of the Brexit campaign, they’d shown an almost-even race, and Leave’s narrow victory (by a margin just under 4 percentage points) was about as consistent with them as it was with anything else. The failure was not so much with the polls but with the people who were analyzing them.

The U.S. presidential election, as I’ve argued, was something of a similar case. No, the polls didn’t show a toss-up, as they had in Brexit. But the reporting was much more certain of Clinton’s chances than it should have been based on the polls. Much of The New York Times’s coverage, for instance, implied that Clinton’s odds were close to 100 percent. In an article on Oct. 17 — more than three weeks before Election Day — they portrayed the race as being effectively over, the only question being whether Clinton should seek a landslide or instead assist down-ballot Democrats:

https://fivethirtyeight.com/features/there-really-was-a-liberal-media-bubble/