Last week an outlier CNN poll claimed Donald Trump had a “big bounce” after his apocalyptic convention in Cleveland. Donald Trump bounces into the lead. The short-fingered vulgarian trumpeted this poll to claim that he had a yuuuge post-convention bounce.
According to Nate Silver at Five Thirty Eight, Trump’s polling average bounce after the GOP convention was 3 to four percentage points. According to Sam Wang at the Princeton Election Consortium, Trump’s polling average bounce after the GOP convention was only one point (see below).
The CNN poll released today claims Hillary Clinton has a 7 point post-convention bounce. Post-convention poll: Clinton retakes lead over Trump:
Hillary Clinton emerges from her party’s convention in Philadelphia with a restored lead over Donald Trump, having earned a 7-point convention bounce, according to a new CNN/ORC Poll.
In a two-way head-to-head matchup, Clinton tops Trump 52% to 43%, and in a four-way matchup including third party candidates Gary Johnson and Jill Stein, Clinton leads 45% to 37% with Johnson at 9% and Stein at 5%.
Nate Silver reports that Election Update: Clinton’s Bounce Appears Bigger Than Trump’s:
Initial polls conducted after the Democratic National Convention suggest that Hillary Clinton has received a convention bounce. In fact, it appears likely that Clinton’s bounce will exceed Donald Trump’s, which measured at 3 to 4 percentage points. Thus, Clinton will potentially exit the conventions in a stronger position than she entered them, perhaps also making up for some of the ground she lost to Trump earlier in July.
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[W]hen evaluating the gains a candidate has made, it’s important to note when the previous poll was conducted. Based on our models, Clinton led by 6 to 7 percentage points throughout most of June, but her lead dissipated to around 3 percentage points by mid- to late July, just before the conventions. Then, after the Republican National Convention in Cleveland, Trump pulled into an approximate tie with Clinton. It’s those post-RNC polls that make for the best comparison when describing Clinton’s bounce.
So far, however, the post-convention polls have been strong enough for Clinton that there isn’t a lot of need to worry about semantics. They suggest that she possibly holds a lead over Trump in the mid- to high single digits, instead of being tied with him. Here are the fully post-convention polls we’ve seen so far:
- A CBS News poll has Clinton ahead by 5 percentage points, in the version of the poll that includes third-party candidates (which is the version FiveThirtyEight uses). Trump led Clinton by 1 point in a CBS News poll conducted just after the RNC, so that would count as a 6-point bounce for Clinton.
- A Morning Consult poll also showed Clinton up by 5 percentage points, representing a 9-point swing toward her from a poll they conducted last week after the RNC.
- A RABA Research national poll, conducted on Friday after the convention, has Clinton with a 15-point lead. RABA Research’s national poll has been something of a pro-Clinton outlier. Still, the trend in the poll is favorable for Clinton. She’d led Trump by 5 percentage points in RABA Research’s poll just after the RNC, meaning that she got a 10-point bounce.
- Finally, a Public Policy Polling survey has Clinton up by 5 percentage points. Because PPP did not conduct a post-RNC poll, we can’t directly measure Clinton’s bounce. But their previous national poll, in late June, showed Clinton up by 4 percentage points. Therefore, their data tends to confirm our notion that the conventions may have reset the race to approximately where it was in June, which was a strong month of polling for Clinton.
Sam Wang at the Princeton Election Consortium reports, Post-Democratic convention bounce:
So far, four five pollsters have released national surveys using samples taken after the end of the Democratic National Convention, and have data from the post-RNC period. The median swing is a 7.0 ± 1.1 2.0 % (± estimated SEM) move toward Hillary Clinton.
The Pre-DNC measurement from PPP was taken in June, predating both conventions. The resulting swing therefore represents a combination of the Republican and Democratic conventions. However, since the median post-Republican convention swing was only 1 point, it was still informative and I included it. Since you can do medians in your head, you can see that this does not make a difference given the current data set.
I have seen some sniffy comments in the news that Hillary Clinton’s post-convention bounce is smaller than Bill Clinton’s bounce in 1992. However, by current standards, Hillary Clinton’s bounce is large. As I wrote the other day, post-convention bounces have been small for presidential elections since 1996, which I suggest is a symptom of political polarization: voters get entrenched in their support.
Donald Trump, like George Costanza, is suffering from “shrinkage.” “I was in the pool! I was in the pool!”