I've been reading Joel's post about Nielsen's plan to offer commercial ratings numbers this fall and I'm thinking that the more finely these numbers get sliced and diced the less usable they're going to be for media buying. After all, you can look at minute by minute commercial ratings but what is that going to tell you? That someone else's ad didn't do very well in a particular time-slot. Those ratings numbers only become useful if the entire commercial buying model is reversed and agencies pay based on how their ad performed according to the Nielsen numbers. Kind of like Google AdWords works now, with advertisers paying for actual performance instead of potential or promised performance. Of course knowing this might be why the networks are acting so eager for Nielsen's data. They don't really have a leg to stand on to protest against this system so they may as well go along and hope no one figures out the weaknesses it presents. Of course that's just speculation on my part.