I agree with most of what you're saying, but would like to point a few things out: 1) Yes, you can track ROIs of that nature, and many people do. But as Stev

I agree with most of what you're saying, but would like to point a few things out: 1) Yes, you can track ROIs of that nature, and many people do. But as Steven Levitt says, it seems to not be a part of corporate culture to do so. And according to him, they often do waste millions. It's not the marketer's money, after all. They'll often say things like, "It's my job to spend the budget" when Levitt points out their losses. 2) There's more to online ads than clickthrough, I agree. I didn't say there wasn't. My point was that the stats are easier to come by, and they'll be harder to weasel up. 3) That is a legitimate concern, I agree. However, being in a marketing arms race should already have been factored into the ROI, IRR, or whatever all-inclusive metric or set of metrics you are basing the budget decisions on. I don't mean Pepsi should give up, or that its marketing budget is bloated, but that even in an arms-race you can go too far.