A CERTAIN SAMENESS:

The Really Smart Phone: Researchers are harvesting a wealth of intimate detail from our cellphone data, uncovering the hidden patterns of our social lives, travels, risk of disease—even our political views. (ROBERT LEE HOTZ , 4/23/11, WSJ)

Advances in statistics, psychology and the science of social networks are giving researchers the tools to find patterns of human dynamics too subtle to detect by other means. At Northeastern University in Boston, network physicists discovered just how predictable people could be by studying the travel routines of 100,000 European mobile-phone users.

After analyzing more than 16 million records of call date, time and position, the researchers determined that, taken together, people's movements appeared to follow a mathematical pattern. The scientists said that, with enough information about past movements, they could forecast someone's future whereabouts with 93.6% accuracy.

The pattern held true whether people stayed close to home or traveled widely, and wasn't affected by the phone user's age or gender.

"For us, people look like little particles that move in space and that occasionally communicate with each other," said Northeastern physicist Albert-Laszlo Barabasi, who led the experiment. "We have turned society into a laboratory where behavior can be objectively followed."

Only recently have academics had the opportunity to study commercial cellphone data. Until recently, most cellphone providers saw little value in mining their own data for social relationships, researchers say. That's now changing, although privacy laws restrict how the companies can share their records.

Several cellphone companies in Europe and Africa lately have donated large blocks of calling records for research use, with people's names and personal details stripped out.

"For the scientific purpose, we don't care who the people are," said medical sociologist Nicholas Christakis at Harvard University, who is using phone data to study how diseases, behavior and ideas spread through social networks, and how companies can use these webs of relationships to influence drug marketing and health-care decisions.

His work focuses on "social contagion"—the idea that our relationships with people around us, which are readily mapped through cellphone usage, shape our behavior in sometimes unexpected ways. By his calculation, for instance, obesity is contagious. So is loneliness.

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