Troves of Personal Data, Forbidden to Researchers

It is “big data,” the vast sets of information gathered by researchers at companies like Facebook, Google and Microsoft from patterns of cellphone calls, text messages and Internet clicks by millions of users around the world. Companies often refuse to make such information public, sometimes for competitive reasons and sometimes to protect customers’ privacy. But to many scientists, the practice is an invitation to bad science, secrecy and even potential fraud.

New York Times.