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Cell phone users secretly tracked in study
WASHINGTON (AP) -- 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 study found that nearly half of the people tracked kept to a circle
little more than six miles wide.
The first-of-its-kind study by Northeastern University raises privacy and
ethical questions for its monitoring methods, which would be illegal in the
It also yielded somewhat 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 done, only describing
the location as an industrialized nation.
Researchers used cell phone towers to track individuals' 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
had tracking devices in them and got records for their locations every two
hours over a week's time period.
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,
according to Rob Kenny, a spokesman for the Federal Communications
Commission. 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 up the field of
human-tracking for science and calls attention to what experts 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."
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
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.
Barabasi said he did not check with any ethics panel. [?!] Had he done so,
he might have gotten an earful, suggested bioethicist Arthur Caplan at the
University of Pennsylvania.
"There is plenty going on here that sets off ethical alarm bells about
privacy and trustworthiness," Caplan said.
Studies done on normal behavior at public places is "fair game for
researchers" as long as no one can figure out identities, Caplan said in an
"So if I fight at a soccer match or walk through 30th Street train station
in Philly, I can be studied," 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
"It certainly is a major concern for people who basically don't like to be
tracked and shouldn't be tracked without their knowledge," Stephens said.
Study co-author 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," 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.
"Despite the fact that we think of ourselves as spontaneous and
unpredictable ... we do have our patterns we move along and for the vast
majority of people it's a short distance," Barabasi said.
The study found that nearly half of the people in the study pretty much keep
to a circle little more than six miles wide and that 83 percent of the
people tracked mostly stay within a 37-mile wide circle.
But then there are the people who are the travel equivalent of the
super-rich, said Hidalgo, who travels more than 150 miles every weekend to
visit his girlfriend. Nearly 3 percent of the population regularly go beyond
a 200-mile wide circle. Less than 1 percent of people travel often out of a
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