Of course, it’s possible for anything to change the outcome of a campaign if the vote is close enough, but the media should treat the battle to “define” Romney with far more skepticism. More generally, reporters should refrain from overstating the importance they place on early-stage campaign squabbles. According to Wlezien and Erikson, the real action comes in the final 100 days, which is when campaign shocks start to “persist to affect the outcome of Election Day” (typically in the direction we would expect given the state of the economy).

In other words, the conventions aren’t just the beginning of the fall campaign; they mark the beginning of the period when campaign events really start to matter. In the meantime, why not help voters learn about the campaign promises that the candidates are making and the agendas they are proposing as they roll out their general election platforms? The horse race won’t be decided now, but the agenda of the next president will be.

Brendan Nyhan is an assistant professor of government at Dartmouth College. He blogs at brendan-nyhan.com and tweets @BrendanNyhan.