- The Washington Times - Thursday, June 5, 2008


Researchers secretly tracked the locations of 100,000 people outside the United States through their cell-phone use and concluded that most people rarely stray more than a few miles from home.

The first-of-its-kind study by Northeastern University raises privacy and ethical questions for its monitoring methods, which would be illegal in the United States.

It also yielded surprising results that reveal how little people move around in their daily lives. Nearly three-quarters of those studied mainly stayed within a 20-mile-wide circle for half a year.

The scientists would not disclose where the study was conducted and described the location only as an industrialized nation.

Researchers used cell-phone towers to track people’s locations whenever they made or received phone calls and text messages over six months.

In a second set of records, researchers took another 206 cell phones that contained tracking devices and obtained records for their locations every two hours over a week’s time.

The study was based on cell-phone records from a private company, whose name also was not disclosed.

Study co-author Cesar Hidalgo, a physics researcher at Northeastern, said he and his colleagues didn’t know the individual phone numbers because they were disguised into “ugly” 26-digit-and-letter codes.

That type of nonconsensual tracking would be illegal in the United States, said Rob Kenny, a spokesman for the Federal Communications Commission (FCC). Consensual tracking, however, is legal and even marketed as a special feature by some U.S. cell-phone providers.

The study, published Thursday in the journal Nature, opens the field of human tracking for science and calls attention to what researchers said is an emerging issue of locational privacy.

“This is a new step for science,” said study co-author Albert-Lazlo Barabasi, director of Northeastern’s Center for Complex Network Research. “For the first time we have a chance to really objectively follow certain aspects of human behavior.”

Mr. Barabasi said he spent nearly half his time on the study worrying about privacy issues.

Researchers didn’t know which phone numbers were involved. They were not able to say precisely where people were, just which nearby cell-phone tower was relaying the calls, which could be a matter of blocks or miles. They started with 6 million phone numbers and chose the 100,000 at random to provide “an extra layer” of anonymity for the research subjects, he said.

Mr. Barabasi said he did not check with any ethics panel. Had he done so, he might have gotten an earful, said bioethicist Arthur Caplan at the University of Pennsylvania.

“There is plenty going on here that sets off ethical alarm bells about privacy and trustworthiness,” Mr. Caplan said.

Studies conducted on normal behavior at public places is “fair game for researchers” as long as no one can figure out identities, Mr. Caplan said in an e-mail.

“So if I fight at a soccer match or walk through 30th Street train station in Philly, I can be studied,” Mr. Caplan wrote. “But my cell phone is not public. My cell phone is personal. Tracking it and thus its owner is an active intrusion into personal privacy.”

Paul Stephens, policy director at the Privacy Rights Clearinghouse in San Diego, said the nonconsensual part of the study raises the Big Brother issue.

“It certainly is a major concern for people who basically don’t like to be tracked and shouldn’t be tracked without their knowledge,” Mr. Stephens said.

Study co-author Mr. Hidalgo said there is a difference between being a statistic - such as how many people buy a certain brand of computer - and a specific example. The people tracked in the study are more statistics than examples.

“In the wrong hands the data could be misused,” Mr. Hidalgo said. “But in scientists’ hands you’re trying to look at broad patterns. … We’re not trying to do evil things. We’re trying to make the world a little better.”

Knowing people’s travel patterns can help design better transportation systems and give doctors guidance in fighting the spread of contagious diseases, he said.

The results also tell us something new about ourselves, including that we tend to go to the same places repeatedly, he said.

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