538: Clinton Gains, And The Polls Magically Converge

irst things first: Hillary Clinton has a 70 percent chance of winning the election, according to both the FiveThirtyEight polls-only and polls-plus models. That’s up from a 65 percent chance on Sunday night, so Clinton has had a good run in the polls in the final days of the campaign. Clinton’s projected margin of victory in the popular vote has increased to 3.5 percent from 2.9 percent.

We’ll continue to collect polls through early Tuesday morning, at which point we’ll update the model for the last time and publish a more philosophical overview on the race. But I’m not sure how much more data we’re really expecting — most of it will probably just be state and national tracking polls that run one last update.

As a lot of you noticed, Nevada, North Carolina and Florida flipped from red to blue over the course of Monday. We don’t think that’s a particularly meaningful metric, because the forecasts are probabilistic — Clinton’s chances of winning Florida increased to 54 percent from 48 percent, for instance, which is nontrivial but not an especially large change. Still, we know it’s something a lot of readers follow. It’s unlikely that any further states will flip to Clinton in our final forecast, as she’s too far behind in Ohio, the next-closest state.1 It’s possible that Florida and North Carolina could flip back to Trump by tomorrow morning, though probably not Nevada, where Clinton’s lead is a bit larger....

Seven of the 19 polls have Clinton leading by 4 points; another four have her ahead by 3 points, then we have a smattering of 1’s, 2’s and 6’s — along with two pollsters, IBD/TIPP and Los Angeles/USC Dornsife, who still have Trump ahead. (We admire the L.A. Times poll for not changing its methodology in midstream, even though the poll has its issues.) On average, Clinton leads by 2.9 points in the polls, although the highest-rated pollsters2 have her a bit higher at 3.8 points, on average. As is usually the case, the range of national polls closely matches the FiveThirtyEight popular-vote forecast.

It’s worth raising an eyebrow, though, when the polls (other than the L.A. Times) show a range this tight at the end of an election, especially given that they’d diverged so much earlier in the campaign. That probably reflects some degree of herding — for instance, because pollsters stick surveys that seem to be outliers in a file drawer rather than publishing them. So the tight range of polls shouldn’t be taken to mean that everyone’s figured exactly how to poll this challenging election just in the nick of time. Still, the polls clearly agree that Clinton is the favorite, and perhaps has a slight wind at her back for Election Day.


http://fivethirtyeight.com/features/election-update-clinton-gains-and-the-polls-magically-converge/