Polls taken during and after the Republican National Convention, which concluded on Thursday in Cleveland, generally show Donald Trump continuing to gain ground on Hillary Clinton, making for a close national race. But it’s customary for candidates to receive a “bounce” in the polls after their convention. There’s not yet enough evidence to come to firm conclusions about the size of Trump’s convention bounce, but the initial data suggests that a small-to-medium bounce is more likely than a large one.
Before we run through the polls, a note of caution: The convention bounce is going to be harder than usual to study this year. That’s because in contrast to 2012, when the polls were extremely steady for weeks before the conventions, they were on the move heading into the RNC this year. In particular, they were on the move toward Trump — or away from Clinton — with Trump whittling down what had been a 6- or 7-percentage point lead for Clinton in late June into something more like a 3-point lead by mid-July.
So when you see a new poll suggesting that Trump has received a bounce, or failed to receive one, you’ll want to be mindful of when the previous edition of the poll was conducted. If the pollster had last surveyed the race in June, odds are that Trump has made some fairly big gains. Some of those were probably realized before the convention and not because of it, however. But if the previous edition of the poll was in July,1 his gains are likely to be smaller.
Keeping that in mind, here’s the data we have so far. First, there are three post-convention national polls, meaning that all of …