The Topline: Was the Trump wave a mirage?

Donald Trump’s poll numbers are slipping in Iowa, and a new national poll is the first in a while to show him trailing. But a closer look at the polling suggests that the Trump wave may have been overstated from the beginning. His sizeable lead has been based largely on the influence of Internet polls. Trump’s summer surge looks far less impressive in telephone polls, and polls of likely voters show his lead was always smaller and is now gone entirely.

Looking across all pollsters and modes of pollsters, Donald Trump leads the field by 10 points, according to the Huffington Post, which averages poll results.  Using only online polls, his lead is even bigger. But narrow the field to just telephone polls, and Trump’s lead over Ben Carson drops to 3 points. Drill down further to phone surveys that talked only to likely voters in the Republican primary, and Carson actually overtakes Trump.

The same dynamic is playing out at the state level. In online polls, Trump is tied with Carson in Iowa, and clobbering him by 26 points in New Hampshire. The telephone polling in both states is markedly different, showing Trump now trailing Carson by double digits in Iowa and leading by half as much in New Hampshire.

Online polls are still relatively new, especially for presidential primaries, but their performance in the 2012 cycle suggests they may exaggerate the rise of surge candidates. Herman Cain, of 9-9-9 fame, owed his entire lead to online polls. Looking only at telephone polls, Cain’s lead shrank from 14 points to just 1 point. The same dynamic was present with both Rick Perry and Newt Gingrich, though to lesser extents.

Fast forward four years, and online surveys make up a much larger share of national primary polling and once again are producing different results. This has had the effect of further boosting Trump, since online polls are now playing a bigger role in the overall average used by poll aggregators. So far this cycle, nine online polling outfits have conducted almost half of all presidential primary polls. In the lead-up to the 2012 contests, there were only two online pollsters producing about a fifth of all national polling.

At the state level, there is even less of a historical record for online polling. In 2012, there were no state online primary polls in Iowa or New Hampshire, one in Florida, and two in South Carolina. The evidence from 2012 is just too thin to say much of anything about the likely accuracy of online, state-level primary polls.

One potential explanation is that online polls may be sampling more non-voters. These non-voters may not be paying close attention and may simply select the candidate closest to the top of their mind. This might also explain why Trump is doing better in phone polls of registered voters than in polls of likely voters.

It’s too early to know which set of polls will prove most accurate, and impossible to know nationally, since there is no national primary against which to measure. When the dust settled in 2012, the phone polls did pretty well in predicting the final margins in the early states where most of the polling is currently happening. The polling world is in a serious state of flux, but nothing appears to have changed so systematically as to suggest phone polls will be way off this time around. But the state contests will give us a good yardstick with which to measure accuracy.

For now, the evidence, both from this year’s polls and from 2012, suggests the Trump bump was smaller than it appeared.

MPG ICMYI

Introducing WBUR Politicker

Last week MPG and WBUR announced the launch of Politicker, a new vertical that will bring together our polling and data analysis with WBUR’s political reporting and commentary. Politicker does for the 2016 presidential race what Poll Vault, our previous collaboration with WBUR, did for the 2014 races here in Massachusetts.

We kicked off the site with our latest poll of the New Hampshire Democratic primary, which found Hillary Clinton retaking the lead in the Granite State on the heels of a strong debate performance. We also asked New Hampshire Democratic primary voters about socialism and electing a socialist president, with some surprising results.

THE CROSSTABS

GOP Debate Primer

Your GOP field, in one GIF, courtesy of Bloomberg Politics.

Republican strategist Stuart Stevens went on NPR’s Morning Edition to preview the GOP debate -- and share his theory that an establishment candidate will end up winning the nomination.

The debate will  be key for the two Floridians in the race, who have seen their fortunes moving in different directions.

Former Governor Jeb Bush has been forced to cut back amidst lackluster fundraising. Before the “reboot” story Bush was most in the news for defending his brother’s honor against attacks from Donald Trump.

Meanwhile, Marco Rubio has been getting another look from potential donors but also coming under fire for missing many votes in the Senate.

The Fix debunks the pro-Trump poll debunkers, while giving a good primer on polling.

And the Dems

Last week, with Vice President Joe Biden announcing he would not run and the marathon Benghazi hearings, may have been even more pivotal for the Democratic campaign than the debate the week before.

But first, FiveThirtyEight’s Harry Enten finds Clinton got the biggest post-debate bounce.

And HuffPost Pollster posits that Clinton stands to gain the most from Joe Biden’s absence from the race.

HuffPost and YouGov found that neither Clinton nor the House Republicans came out of the Benghazi hearings much improved, and that opinions of the hearings split along party lines.

We may have lost Onion Joe Biden from the presidential race, but Onion Hillary Clinton is ready to pick up his supporters.

Trick or Treat

And finally, HuffPost and YouGov set out to determine America’s favorite Halloween candy.

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Tableau game respects Tableau game: GOP Debate host CNBC is out with a very impressive set of data vizzes of the presidential fundraising and spending, including how much each candidate spent per point in the polls, where each candidates’ donors live and what they do for work, and what the candidates’ are spending on and where.