538: Election Update: National Polls Show The Race Tightening — But State Polls Don’t

Hillary Clinton moved into a clear polling lead over Donald Trump just after the Democratic convention, which ended on July 28. Pretty much ever since, the reporters and poll watchers that I follow have seemed eager to tell the next twist in the story. Would Trump’s numbers get even worse, possibly leading to the first double-digit victory for a Democratic presidential candidate since 1964? Or would Trump mount a comeback? As of last Tuesday, there wasn’t much evidence of an overall shift in the race. Trump was gaining ground in some polls but losing ground in a roughly equal number of them.

Since then, Trump has gotten some slightly better results, with national polls suggesting a race more in line with a 5- or 6-percentage-point lead for Clinton instead of the 7- or 8-point lead she had earlier in August. But state polls haven’t really followed suit and continue to show Clinton with some of her largest leads of the campaign. Trump received some decent numbers in Iowa and Nevada, but his polls in other swing states have been bad.

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You can, of course, pick apart the individual polls if you like. The USC/Los Angeles Times poll makes some unorthodox methodological choices; I happen to like some of these choices and dislike others, but overall, they produce a poll that’s significantly more Trump-leaning than other pollsters. And I’m not sure anyone should be crowing about Zogby Analytics polls, which have been highly inaccurate historically. But there are ways to adjust for these things, and they don’t obscure the fact that the trend in national polls has mostly been toward Trump.

State polls tell another story, however. Here’s every state poll we’ve added since Tuesday:2

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Moreover, these state polls show highly favorable trend lines for Clinton, where they’re available. Among the six polls that had previously surveyed the same state, Clinton gained ground in every one, with an average swing of 6 percentage points toward her. A caution: The average shift is inflated by a Quinnipiac poll of Colorado which found Clinton up 8 points; Quinnipiac had implausibly showed an 11-point lead for Trump when it surveyed the race in November. Even without that poll, however, Clinton’s average gain is 4 percentage points, still pretty good.

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http://fivethirtyeight.com/features/election-update-national-polls-show-the-race-tightening-but-state-polls-dont/