IRCPPS in the Links: How US Political Campaign Advertising Works

John Sides writes on the subject in 538:

So what do we know about campaign advertising? There is a better answer to this question. Just as Mr. Beane turned to math geeks, we can turn to a different species of geek: political scientists. Here are the lessons of their research about when campaign advertising does and does not matter.

1. Campaign ads matter more when the candidates are unfamiliar...
2. Campaign ads matter more when a candidate can outspend the opponent...
3. Campaign ads can matter, but not for long...