Primary Season Was Full of Surprises. Here’s Why the Polls Missed Some of Them.

Ayanna Pressley’s blowout victory over a 10-term congressman last week was the latest example of a trend that has become abundantly clear: 2018 is the year of the progressive insurgent, from Alexandria Ocasio-Cortez to Andrew Gillum.

But if you relied exclusively on polls, you may not have seen these results coming. A survey conducted in late July, more than a month before the election, showed Ms. Pressley losing by 13 percentage points; she ended up winning by 17. The last poll conducted by Representative Joseph Crowley showed him beating Ms. Ocasio-Cortez by 36 percentage points, but she ended up beating him by 15 in June.

We asked four experts what could have made the polls seem so wrong. CONT.

Maggie Astor, New York Times