Are We Judging Banner Advertising Unfairly?
All online advertisers want to see results from their online campaigns. Most often, what direct response advertisers want to see is a certain type of behavior among their prospects: Prospect sees ad. Prospect immediately clicks on ad. Prospect converts on the website.

But what if prospects don't necessarily want to click on an ad the second they are exposed to it? What if the conversion happens at some later date, as a result of the ad exposure?
http://www.clickz.com/media/media_buy/article.php/824291