The press loves statistics because they give a story the patina of fact, of being based on firm and undeniable proof. But as last week's frenzied and contradictory media coverage of Kerry's anticipated "bounce" in the polls showed, there is always more than one way to read the numbers.
Depending on your news source, Kerry either received "no bounce" (CNN), a "baby bounce" (Newsweek), or a "big bounce" (American Prospect) based on four different post-convention polls. Adding to the confusion, three of the polls showed gains for Kerry while one (the CNN/USA Today Gallup poll) revealed a drop. Clearly, a number of political motives are at play in the interpretation and selection of these statistics, so to get an accurate idea of how Kerry actually fared we need to take a look at the facts.
First, what is a "bounce" and why does it matter? The term refers to a trend in the last 50 years of candidates who, after accepting the party's nomination and naming a running mate, witnessed a dramatic (and often temporary) boost in the polls. In 1984, Walter Mondale surged nine points after the convention, and, in 1992, Bill Clinton received an incredible 13 point bounce. Historically, this boost reflected the excitement of ending a long, hard-fought primary season and completing the party's ticket.
A number of factors made this year's Democratic race—and Kerry's opportunity for a bounce—different from the past. Because of an accelerated political calendar that allowed states to hold primaries in February, Kerry wrapped up the nomination much earlier than previous candidates. He thus named his running mate earlier, and was able to whip up support long before the convention gavel. Kerry's bounce came after the Iowa caucuses, when he leapt 12 points to take the lead over Bush, 52 percent to 44 percent. Since then, he has remained equal or ahead of the president in the polls.
Kerry's lack of a huge post-convention bounce also reflects the dwindling number of voters who have not already made up their minds. (A recent ABC/Washington Post poll put the figure at 7 percent.) Yet on individual issues, Kerry made huge gains on Bush—he now leads in everything but "the campaign against terrorism," according to ABC—and Newsweek reported that independents favor Kerry 45 to 39 percent.
But at its root, the "bounce" story is essentially meaningless. Professor Philip Klinkner of the Hamilton College told MSNBC that "There's no relation between bounce and election outcome." The attention it's gotten probably has more to do with the shrewd, expectation-priming announcement by Republican strategist Matthew Dowd that "Kerry should have a lead of more than 15 points coming out of this convention" three weeks ago than any value it has as a political predictor.