According to researchers at Northeastern University in Boston, Massachusetts, most people rarely venture more than a few miles from home. And these researchers know what they're talking about. Two years ago, in some unnamed country outside the US, they acquired six months of cell phone records describing the daily movements of more than 100,000 people.
With a study called "Understanding individual human mobility patterns," published in this month's edition of Nature, Marta González, César Hidalgo, and Albert-László Barabás provide at least a little insight into the travel habits of the average human, but they've also rung a few privacy alarms at places like The Associated Press and the Electronic Privacy Information Center.
The researchers acquired those phone records from a mystery service provider in "a place with a high cell phone penetration." All we know is that this place wasn't in the States. In most cases, they approximated customer movements by pinpointing the cell towers routing their various calls and texts. But roughly 200 cell customers had signed up for services that actively track their location at regular intervals. And the researchers tapped into this data as well.
"Let's a say a phone company has a service that tells you how your allergies might respond in a given location," Hidalgo told us. "When you subscribe to that service, you allow the company to track your position. We used this sort of thing as a complementary data set."
The data showed that nearly three quarters of those 100,000 cell customers moved "mostly" within a 10 mile radius of home. Mostly means about 67 per cent of the time.
But Hidalgo and his fellow researchers also found there's a significant swath of the population that behaves quite differently. Between 2 and 3 per cent of those studied "regularly" traveled to locations more than 100 miles away. Regularly means almost every week. In other words, the study proves the existence of jet-setters and business travelers.
If this doesn't interest you, perhaps the privacy debate will.
Hidalgo is adamant that no one's privacy was compromised. All the data was anonymized, he says, before the service provider turned it over. "We didn't have names or phone numbers. Just anonymous ID codes." And he points out that all 100,000 cell customers signed a contract that said the service provider could use their data for "internal research purposes."
We would argue that a study by outside academics is not internal research. But Hidalgo sees things differently. "We were operating inside the company," he told us.
Assuming that Hidalgo is stretching the definition of internal, his study would have been illegal in the US. As FCC spokesperson Rob Kenny told us, Section 222 of Communications Act says that cell outfits can't disclose wireless location information without "the express prior authorization of the customer." And the situation is much the same in the EU.
One problem with the study, says EPIC's Marc Rotenberg, is that there's no way of knowing whether it broke the law. "The researchers are very reluctant to describe how the data was obtained and who was involved," Rotenberg told us. "Methods should be public and provable. How else do you determine if it was legal?"
But even if the study was legal, this was hardly an example of anonymous data aggregation. After all, this was a study that sought to determine where people live. "How could they not know who they were studying if they had latitude and longitude?" Rotenberg said. ®