Were Obama’s Early Ads Really the Game Changer?
Nate looks at the data to find that the answer is “probably not”.

The problem, however, is that there is very little evidence that these early ads mattered much, according to research I have done along with Lynn Vavreck, a political scientist at the University of California, Los Angeles, for an upcoming book, The Gamble.

Some of that evidence comes from political science research into other campaigns, including presidential races. As I noted here over a year ago, this research finds that political ads have short-lived effects. If during one week a candidate broadcasts significantly more advertisements than the opponent, that candidate may see a boost in the polls, but the effect of that advertising will be mostly gone within a few days. Political ads are a bit like morphine: you need dose after dose for them to keeping working.

In the 2012 campaign, what is most striking about the polls during the spring and summer months is how stable they were.