Will Mitt Romney get a "bounce" out of the Republican National Convention? That's a question on the minds of many political reporters and political strategists as they wait for the proceedings to get under way after a day's delay caused by Hurricane Isaac.
"Bounce" is the term that pundits use to describe the rise in the polls that most, but not all, Republican and Democratic nominees have enjoyed after three or four days of dominating the political news at their quadrennial conventions.
The bounce phenomenon was unknown through the middle 1960s. Public polls were few and far between, providing no benchmark from which to measure the effect of the convention.
And in those days, when there were real fights for the nomination at conventions, the nominee and his campaign did not have the monolithic control over the proceedings that most nominees in the last 40 years have had.
Gallup, the organization that has been in the polling business longer than any other, has been measuring convention bounces since 1964.
Over the years, Gallup reports, Democratic nominees have gotten a 6-point bounce from their conventions and Republicans a 5-point bounce.
The figures even out, however, if you eliminate the 16-point bounce Bill Clinton got from the July 1992 Democratic convention in New York. That came after independent candidate Ross Perot, who had been leading in polls in the spring, suddenly withdrew from the race and endorsed Clinton.
But although the two parties have gotten the same average bounce, there is more variability for Democrats than Republicans.
Republican nominees, according to Gallup, have gotten a bounce of between 4 and 8 points in 10 of the 12 national conventions since 1964. The two exceptions: Bob Dole got 3 percent in 1996, after being hammered by the Clinton campaign in negative advertisements all spring, and George W. Bush got only a 2-point bounce in 2004, a year when, most analysts agree, almost all voters were strongly committed before the conventions began.
Some Democratic nominees got bigger bounces than any Republican -- Clinton, Jimmy Carter in both 1976, when he was a fresh face, and 1980, when he faced a challenge from Edward Kennedy, and Walter Mondale in 1984.
But George McGovern got no bounce at all after the tumultuous and chaotic 1972 national convention. Few voters saw his stirring acceptance speech, which was delayed until 3:00 a.m.
And in the polarized year of 2004, John Kerry's bounce was a negative 1 point. His emphasis on his military record evidently didn't help.
Incumbents get about the same lift as nonincumbents' bounces, but the latter vary more. Some new faces go over well, while others thud.
Is there a correlation between the size of the bounce and the vote in November? Certainly there was for Clinton in 1992, and the no-bounce Democrats -- McGovern and Kerry -- both lost. But in five of the 12 races since 1964, the loser had the larger bounce.
Will Romney get a bounce? By this time next week, we'll see, but more important is whether he can hold on to most of it until Nov. 6.