FiveThirtyEight: How Early Primary Polls Foreshadowed Surprises Like Obama’s Rise And Trump’s Win

Because pollsters ask questions in different ways and ask about different lists of candidates, our methods of estimating name recognition had to be treated as rough estimates, so the candidates in each primary cycle have been sorted onto a somewhat subjective five-tier scale to sum up their level of fame.3 These name-recognition scores are represented as five square boxes in the table below, where more black boxes means higher levels of name recognition. (Because these scores can adjust a candidate’s average upward but not downward, the adjusted polling average will add up to more than 100 percent).[...]

But the bigger story in the 2016 cycle was arguably the rise of now-President Donald Trump in the GOP primary field. Prior to his campaign announcement in June 2015, Trump was polling in the low single digits. But the 2016 Republican field was arguably the most crowded one ever, and there was no clear frontrunner. In the first half of the year, seven (!) candidates were polling at more than 10 percent in the adjusted polling average, with Wisconsin Gov. Scott Walker and former Florida Gov. Jeb Bush leading the way. But in the second half of 2015, Trump shot up to take the lead while candidates such as Bush and Walker fell sharply. Trump’s increase from an average of 3 percent in the first half of 2015 to about 29 percent in the second half — using either the regular or adjusted polling average — represents the largest increase from the first half of the year to the second half for any candidate in the 1972 to 2016 period. And once the primary voting started in 2016, Trump consistently won pluralities in most of the early contests, which positioned him to withstand efforts among some in the GOP to stop him from winning the party’s nomination. He then, of course, went on to defeat Clinton in the general election. [...]

So now we’ve gone through every cycle from 1972 to 2016 and found that the early polling leader often went on to win a party’s nomination, and the early polls, once they were adjusted for name recognition, often foreshadowed the rise of notable candidates. In the final part of our series, we’ll move beyond the descriptive and dive deep into the trends that emerge from the entire 1972 to 2016 period, drawing some statistical conclusions about how meaningful early primary polls really are.

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