Cell Phone Networks and Privacy Issues

Here is a new networks paper that just came out in Nature. It is by one of the usual suspects (Barabasi), an up-and-coming postdoc (Marta Gonzalez), and somebody else (of whom I've never heard). One of my networks buddies at Oxford has done some related work in the past and is in fact involved on the follow-up work to this paper. (One of the new postdocs here was hired for this project as well.) There are some pretty dicey ethical issues involved in this one, and the author with the unfamiliar name has seemingly shot himself in the foot with one of his comments in which he mentioned basically that there are nefarious things one could do with that data so that it's a good thing that it's scientists who are using it and not someone else---that was really not a smart thing to say. (Unsurprisingly, by the way, this paper is getting a ton of press.) Here are the title and abstract:

Title: Understanding individual human mobility patterns

Authors: Marta C. González, César A. Hidalgo, & Albert-László Barabási

Abstract: Despite their importance for urban planning1, traffic forecasting2 and the spread of biological3, 4, 5 and mobile viruses6, our understanding of the basic laws governing human motion remains limited owing to the lack of tools to monitor the time-resolved location of individuals. Here we study the trajectory of 100,000 anonymized mobile phone users whose position is tracked for a six-month period. We find that, in contrast with the random trajectories predicted by the prevailing Lévy flight and random walk models7, human trajectories show a high degree of temporal and spatial regularity, each individual being characterized by a time-independent characteristic travel distance and a significant probability to return to a few highly frequented locations. After correcting for differences in travel distances and the inherent anisotropy of each trajectory, the individual travel patterns collapse into a single spatial probability distribution, indicating that, despite the diversity of their travel history, humans follow simple reproducible patterns. This inherent similarity in travel patterns could impact all phenomena driven by human mobility, from epidemic prevention to emergency response, urban planning and agent-based modelling.


The overall result (about how predictable we are) isn't surprising at all, but what is really nice is more specific quantitative information about such regularity--probability distributions, etc.--that could be really helpful for things like designing vaccination strategies.

I'm not planning to give my thoughts on the ethics of the study in the entry itself (though I'll consider doing so in the comments if an interesting discussion arises (as I hope it will). This is certainly one of those studies that ought to provoke such a discussion.