Did the conventions change any minds?

Since 2004, conventions have taken place later in the season, and the practice of separating them by a few weeks has long fallen by the wayside. That created a 10-day blur of convention coverage, challenging campaign officials who are looking for some way to break through. And by Labor Day, the holiday that separated the two conventions this year, voters are much further along the decision-making track and, particularly in swing states, are awash in information about the candidates.

“I think they have absolutely no impact on election results whatsoever,” said Allan J. Lichtman, a history professor at American University in Washington. “And people are catching on these conventions don’t matter. They are just daylong infomercials. People are beginning to realize that.”…

There is a very narrow band of voters who might genuinely be open to argument. But officials with both campaigns said they were concerned that the television audience was made up overwhelmingly of friendly crowds looking to cheer on their team: Republicans tuned in last week, and Democrats this week.

More than anything, given the fire hydrant spray of information hitting voters from so many different sources, the half-life of even the biggest events is diminishing.