A recent Wall Street Journal article, “When ‘Likes’ Can Shed Light,” stated:

Patterns of “Likes” posted by people on Facebook can unintentionally expose their political and religious views, drug use, divorce and sexual orientation …

My first response was, “Duh, of course!”  But I think the implications are much deeper.  A wide range of disparate conditions can be linked together to imply seemingly distant results.  For example:

“Likes” for Austin, Texas; “Big Momma” movies; and the statement “Relationships Should Be Between Two People Not the Whole Universe” were among a set of 10 choices that, combined, predicted drug use. 

“Likes” for swimming, chocolate-chip cookie-dough ice cream and “Sliding On Floors with Your Socks On” were part of a pattern predicting that a person didn’t use drugs.

… arises from an emerging discipline in which experts sift through extremely large digital data sets, such as collections of web searches or Twitter messages, for subtle patterns and relationships.