To be honest, Macy's a century ago of course wanted data on conversions from newspaper ads. They could ask some customers whether they had seen the ad prior to

To be honest, Macy's a century ago of course wanted data on conversions from newspaper ads. They could ask some customers whether they had seen the ad prior to going to shop. They could print coupons that you need to physically bring in to get a deal. They could pay agencies like Gallup to run more comprehensive customer research. Shooting in the dark is a so-so strategy, and every business strives to do things in a more cost-efficient way. (Corollary: if you want businesses to stop building dossiers on you, you have to make it unprofitable.)