Did you ever think about just how advertising really works, compared to how we often measure it? Suppose you see 55 different ads over three weeks for Joe's Junk, but when you finally click on a banner ad and buy some of that Junk, it's the very last ad -- the one you clicked on -- that gets all the credit.
This measurement problem is called the Last Ad Problem, and you ought to run right over to iMedia Connection and read Mark Hughes' article "Facebook to GM – “Got Measurement?” (Ford Does)" for an eloquent explanation. Some nice discussion of Facebook's recent situation with GM pulling their $10 million ad budget, too. You'll learn a bit about attribution modeling, and the concept that a team of ads actually influences a purchase. --WTP