Trying to quickly understand how well an online advertising campaign is doing is important.
There are a lot of factors to look at, to make sure that it is working, and a lot of methods to use to test those ads.
A patent application from Advertising.com describes one method they are using:
Systems and methods of achieving optimal advertising
United States Patent Application 20050289005
Inventors: John B. Ferber, Scott Ferber, Mark Hrycay, and Robert Luenberger
Published December 29, 2005
Filed: May 18, 2005
A system and method for achieving optimal advertising is disclosed.