Mosaic Theory

A method of analysis used by security analysts to gather information about a corporation. Mosaic theory involves collecting public, non-public and non-material information about a company in order to determine the underlying value of the company's securities and to enable the analyst to make recommendations to clients based on that information.
-Investopedia

In advertising this is known as data-mining. Does it work?

The New York Times ran a story last year about how a man angrily confronted a Target stor manager to complain that the company was sending his teenage daughter coupons for baby goods. Were they trying to encourage her to get pregnant? Nope. Target's data-mining operation had found a strong correlation between purchases of about 24 items- scent free lotions, certain nutritional supplements, and so on- and different stages of pregnancy. The teenager's purchases had fit the pattern. The teenager's father apologized to Target a few days later, when it turned out that his daughter was, in fact, pregnant.
-Glenn Harlan Reynolds, December/January issue of Popular Mechanics

I guess it works but where could it lead? The real question is where shouldn't it lead? Big brother is already spying on us although Microsoft seems to be doing something to counteract that.