Cell Phone Data: Can You Track Me Now?
STEVE INSKEEP, host:
I suppose if Evan Lysacek put a cell phone in his pocket, researchers might be able to use it to track the path of his dramatic jumps, because researchers have been using cell phone information to stay tuned in to people's movements. A new study looked at people's daily travel patterns and found they are extremely predictable, even if people appear to roam around.
NPR's Nell Greenfieldboyce reports.
NELL GREENFIELDBOYCE: Laszlo Barabasi is a researcher who studies human behavior. One of the things he wants to understand is how much of people's daily routine is predictable. He knew that people with jobs generally spend most of their time at work or at home, asleep. After all, his own life isn't exactly random.
Professor LASZLO BARABASI (Complex Network Research, Northeastern University): So when I started this research, my expectation was yes, of course I am terribly regular, but I know that there are other people out there who are very spontaneous.
GREENFIELDBOYCE: He and his colleagues got a surprise, though, when they went looking for those supposedly spontaneous, freewheeling people.
Mr. BARABASI: And the surprise was that I could not find those, at least the data was not showing those individuals.
GREENFIELDBOYCE: Even though he had a lot of data to search through. Barabasi works at Northeastern University in Boston. He's been studying people's travel patterns, using massive amounts of billing data provided by a cell phone carrier for a European country.
Prof. BARABASI: We don't have names. We don't have phone numbers. We don't have characteristics of the individual.
GREENFIELDBOYCE: But they can follow an individual's movements, because every call must go through a nearby cell phone tower. His team recently tracked 50,000 people who use their cell phones fairly frequently.
Prof. BARABASI: Most people travel very little on a daily basis, you know, five to 10 kilometers or so. There were a few individuals, who on a daily basis, travel hundreds of kilometers.
GREENFIELDBOYCE: He had thought that the homebody's daily routine would be easy to predict, while the frequent traveler's would be much harder. But his analysis showed that this wasn't the case.
Prof. BARABASI: We were seeing an average of 93 percent predictability across the user base. What does it mean? That means that for the vast majority of the people, you could, in principle, write an algorithm that could predict 93 percent of the time, correctly, their present location.
GREENFIELDBOYCE: And they didn't find anyone whose predictability was below 80 percent. Barabasi says people lead all kinds of lives rock star, company CEO, accountant.
Prof. BARABASI: But when it comes to our daily pattern, you likely are just as predictable as the person next to you, or the one who you think is much less or much more predictable.
GREENFIELDBOYCE: The researchers described their study in the journal Science. Nathan Eagle is at the Santa Fe Institute. He recently used cell phones to study the predictability of people's movements around a university campus. He says this new study is impressive because of its much larger scale.
Mr. NATHAN EAGLE (Postdoctoral Fellow, Santa Fe Institute): This is the first that I know of, that that really kind of showed it on a nationwide level, almost.
GREENFIELDBOYCE: He says studies like this one show the power of cell phone information for revealing large-scale patterns of human behavior. And major carriers around the world are now starting to share some of their data with scientists.
Mr. EAGLE: I think I've got one of the larger data sets. And we have now, I think, access to close to half a billion individuals, essentially - or at least data on half a billion individuals.
GREENFIELDBOYCE: And he notes that worldwide by the end of the year, the number of cell phone subscriptions is expected to hit 5 billion.
Mr. EAGLE: It's insane. I mean, the vast majority of our species are carrying around a little device that's continually logging their behavior.
GREENFIELDBOYCE: He says this could aid public policy, helping governments make decisions about things like transportation. And scientists also have a new way to study differences across cultures. For example, he says people's travel routines may be predictable in Europe, but maybe that's not so true elsewhere.
Nell Greenfieldboyce, NPR News.
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