Polls & predictions

Ranking the 2016 Presidential Primary Polls and Predictions

After more than 50 million votes cast in 100-plus nominating contests since early February, the U.S. presidential primary season is over and each major party finally has its presumptive nominee. Now, as the country prepares for the race between Democrat Hillary Clinton and Republican Donald Trump, and braces for a flood of polling and prognostications regarding who will win, how might we begin to separate the signal from the noise and avoid failing predictions, like the majority of Brexit polls that mistakenly saw Britain remaining in the European Union?

To find out which outlets did the best job of predicting the primary winners in this wild cycle, Bloomberg Politics examined hundreds of polls as well as nearly 300 final projections from four predictors across a big set of 90 nominating contests (see methodological note at the bottom of this story) and a small set of 52 contests that every predictive source weighed in on.

The verdict: a tie, when looking at the small set, between PredictWise, an aggregator of betting-market data, and FiveThirtyEight, whose “polls-plus” prediction model includes statewide polls, national polls, and endorsements. Both were right 92 percent of the time across those 52 primaries and caucuses.