But this sort of data is so powerful that it produces results far more powerful than traditional advertising. For instance, Facebook offers the chance to pay not just for a certain audience size, but an actual
business outcome, like a sale, an app download, or a newsletter subscription. Once upon a time advertisers paid a “CPM” — cost per thousand views — for a marketing campaign.That was just the chance to get in front of people. Now Facebook offers a rate based on “CPA,” or “cost per action,” a once-unimaginable metric offered because the company is so confident in its understanding of people and their preferences that Facebook can essentially guarantee a certain number of people will do certain things.