AdSense is a toughie. Yahoo has a competitive analytics package (http://web.analytics.yahoo.com/ http://web.analytics.yahoo.com/), and really, Bing results are

AdSense is a toughie. Yahoo has a competitive analytics package (http://web.analytics.yahoo.com/ http://web.analytics.yahoo.com/), and really, Bing results are generally just fine. Sure, it'd be harder, but that's the point of the experiment.