Looking closer at the nature of the rebuttals, we find them nearly twice as likely as the average to appear on op-ed pages, 17% versus 9% overall.

The network evening newscasts were also unusually likely to refute prevalent character themes about the candidates. Nearly 20% of all the rebuttals came on the evening news, even though the newscasts made up only slightly more than 10% of all character statements. One possibility is that the nightly newscasts, given their limited time, now often see their role as responding to or deflating the conventional wisdom that has built up during the news day.

Who were the sources of the rebuttals? One might have thought candidates or their surrogates would have carried the weight. Not so. The sources were similar to those for all the themes, about a half from journalists, a quarter from candidates, 10% from surrogates, 9% from outside experts and 6% from voters.

One might have also expected that a rebuttal would have to carry more evidence than the charge it was refuting. Again, not so. Rebuttals were a little less likely than the average theme, to offer some form of evidence (73% versus 81%) and less of it tended to be the candidate's public record, 19% versus 26%.