We no longer need rooms full of people or telemarketing campaigns. The Internet lends itself to even a more finite way of perfecting the art of isolating demographic groups. We not only just track buyers by their preference, age, gender, geographical location and financial class, but by how they came to our door. Wrote a number on a piece of paper from a friend's newspaper at lunchtime and really don't remember if it was the Post or the News. Plus, when this is done manually the info itself is taken at a level and that mostly depends on how good the operator is, or if they hit the right key when then punched it into the system.
Internet tracking is much different.
Put a site out there, throw a counter on it and see how many hits it took to make a sale. We already knew how many unique visitors it took to make a sale. We needed to have much more information to market a product on the Internet then in the brick and mortar world. The big budget advertisers have it down to a mathematical science. TV, Radio and newspaper ads go out in a controlled environment.