Cell Phone Calls Show Humans Are Very Predictable
Two figures representing a cell phone user who made calls in the vicinity of 22 call-routing towers (left) and 76 towers (right). Each dot represents a tower and the numbers what percentage of calls came through that tower.
CREDIT: Chaoming Song
If you feel like you keep going to the same places and doing the same things, you're right. A recent study used cell phone records to show that peoples' movements from one place to another can be predicted 93 percent of the time.
While revealing our lives as rather repetitive, the research could help usher in "super"-smart phones , better traffic flow control and eventually assist in the tracking of epidemics street-by-street.
To figure out where we go day-in and day-out, researchers obtained cell phone records of 50,000 anonymous individuals from a mobile phone company. The pattern of the movements by cell phone owners was traced over a three-month period based on the nearest cell phone tower that routed their calls.
More than nine times out of ten, the location of any single person at a certain time of day could be correctly guessed, the study suggests. Even those people who traveled long distances each day, and therefore had greater opportunity to deviate from their paths, rarely did so beyond a predictable pattern that emerged over time.
Essentially, the research showed that "if you know where I've been and where I am, you have a good idea where I'm going," said study co-author Nicholas Blumm, a graduate student at the Center for Complex Network Research (CCNR) at Northeastern University in Boston, Mass. in a prepared statement.
The roads well-traveled
To begin with, the location of someone more than two-thirds of the time is reasonably easy to predict: eight hours at work, eight hours at home asleep and a regular route to and from work, for instance. Yet in the remaining portion of the day – and unexpectedly on weekends, too – we show little variation among the locales we frequent.
"To our surprise, we find a whopping 93 percent predictability across the whole user base," said Chaoming Song, a physicist at CCNR and another of the paper's authors. "And we do not observe individuals whose potential predictability goes significantly under 80 percent."
In other words, even the most footloose among us do not venture much off of our own beaten trails. "We find we are all in one way or another boring," said Albert-László Barabási, corresponding author of the paper and director of CCNR, in a prepared statement. "Spontaneous individuals are largely absent from the population."
As the mobile phone towers in the study had reception areas of about a square mile, the method in the study for gauging people's locations is a bit inexact, the authors point out. This means that actual stores or parks, say, where pedestrians might make a number of local stops cannot be readily foreseen by the cell phone-enabled model.
Also, peoples' trajectories can be mapped only by the cell phone calls dialed during their daily routines (and occasional diversions). To cut down on these errors related to a lack of location information – that is, people whose cell phones often stayed in their pockets rather than to the sides of their faces – the researchers first analyzed chatty phone owners who made calls every two hours on average. These heavy-users helped shape the overall model for those who made far fewer phone calls.
Such finer details might be helpful in a number of technological applications, the authors say. However, the overall finding that we opt for familiar haunts over and over can already be made useful.
"We show that this high predictability is partly rooted in what we call the 'regularity' in the mobility pattern," Song told TechNewsDaily, which "captures the likelihood that we return to the same locations repeatedly."
The power of hither and thither
This insight into our behavior could lead to technologies such as "super"-smart phones that predict where an owner is going, notifying him or her of sales at the mall destination, for example, or of traffic jams along the way. An accurate place-picking phone could even let users know if a friend is at that mall, Blumm suggested.
Besides news of sales or buddies' location, the authors think their research can be applied to halting the spread of epidemics , given that human carriers of disease can be found more than 90 percent of the time based on where their cell phones say they will be.
The research was published in the February 19 issue of Science.