By Matthew Chen October 26, 2016
In our most recent post, we noted that Clinton will almost surely win this election, based on analyzing the results of polls taken after the first debate. Now that all three debates have concluded and post-debate polling results have been published, we can attempt to make a more precise prediction about exactly how many electoral votes Clinton will actually win.
Based solely on the objective results of our model, Clinton will most likely win 334 electoral votes. While there are many different combinations of states she might win that would lead to this result, here's the most likely one:
334 electoral votes would be very close to the 332 electoral votes that Obama won four years ago, but Obama's map looked completely different. That shouldn't necessarily be surprising; while Clinton and Obama have very similar bases of support, Romney and Trump aren't anywhere nearly as closely aligned (to say the least.)
In any case, the probability that the electoral map looks exactly like this is exceedingly small. It will probably look similarly, but there are number of states which could easily go for the candidate opposite who we expect. Georgia, Iowa, and Ohio have had wildly fluctuating poll results, and other states like Arizona have consistently shown a very tight race, meaning that an almost-equally likely electoral map for Clinton might look like this:
Of course, it could also look very different. And since the combinations of states that lead to 334 electoral votes for Clinton are much more likely than those that lead to 374 electoral votes, our model predicts that the probability Clinton wins exactly 374 electoral votes is vanishingly small—only 0.2%.
It's important to note that the probability distribution of electoral votes for Clinton isn't symmetric. Clinton has a 62% chance of winning more than 334 electoral votes, versus only a 31% chance of winning fewer than 334 electoral votes. In fact, Clinton will probably not win exactly 334 electoral votes; however, she is likely to win at least that many, and possibly many more - up to about 400 electoral votes.
Moreover, the race is still changing. Clinton performed better than Trump in most—if not all—of the debates based on the subsequent polling, and not every state has had a high-quality poll conducted within it in the past two weeks. As a result, it's possible that some of the polls we used as input in our model don't accurately reflect the extent of Clinton's lead over Trump. Over the next week and a half, we expect more data to come out that will allow us to make a more confident prediction.
Images generated via 270ToWin.