I have been writing about bounces since 2008 at openleft. I wrote the following at bleeding heartland last monday
here.
The average bounce since 1996 is 6.2 points. You will see different numbers, though if you read the piece you will see some of those fail to really understand the entire process.
Essentially convention bounces are the product of two events: the VP selection and the Acceptance Speech. That makes calculating this bounce complicated as Clinton named Kaine in the same time frame as the post GOP Convention.
The best was to get a sense of the bounce is to compare the same poll pre and post convention. So here goes:
CBS, 7/22-24, Trump 44, Clinton 43, Prior poll 7/16 40-40. Bounce Trump +1
CNN, 7/22-24 Trump 48, Clinton 45. Prior 7/16 Clinton +7. Bounce Trump +10
Morning Consult: Trump 44, Clinton 40, Prior Clinton 41, Trump 39. Bounce Trump +6
RABA, Clinton +5, was Clinton 41, Trump 29. N
Bounce +7
So the average bounce is: Trump +6. Which is just about the average bounce since 1996.
Just on the surface it looks to me that the polling that showed Clinton with larger leads no agrees with polling showing a tight race.
Make no mistake, though. Despite all of the posts in liberal blogsphere about what a disaster the GOP convention was, it was anything but.
I think the Democrats will get a larger bounce in part because Sanders will help. But a great deal is riding on Clinton’s speech on Thursday.