How Much Will the Debate Shift the Polls? Here’s One Calculation
How Much Will the Debate Shift the Polls? Here’s One Calculation
In my snap predictions last night, I was wrong about one thing: the post-debate insta-polls definitely suggest that most debate viewers believed Romney won: CNN had it 67-25. A second poll of uncommitted voters conducted by CBS and Knowledge Networks scored in 46-22 for Romney. (My second prediction—that the media would reach the same conclusion—turned out better.) One caveat is that insta-poll results don’t necessarily correlate with debate bumps in the polls, as Harry Enten shows. But still: these results obviously aren’t what Obama wanted.
My ultimate prediction was that Obama’s lead in the polls—now about four points—would narrow by about 1 point. Does that still seem reasonable? Here’s another take. The political scientist Joe Cera looked at the first debate in 2000—one that appears to have moved the polls, as I noted in my piece. Using a large panel of respondents interviewed before and after the debate, he shows that Bush gained about 3 points, all of which were taken from the pool of undecided voters. The undecideds shrank from 12% to 9%. 2000 is a useful comparison because roughly similar fractions of people thought Bush had won—57%—as thought Romney won (57% is about what you get averaging the CBS and CNN polls above—with the caveat that they were sampling from different populations).