Ask yourself this: Are you a statistic or a specific example? That's the question being raised in the aftermath of a study in which researchers secretly tracked the locations of 100,000 people to determine their movement patterns. Such studies are considered invasions of privacy -- and illegal -- in the United States, but this one was done in an undisclosed industrialized nation. The subjects were chosen at random out of a pool of 6 million from a mystery wireless provider and tracked based on cell tower triangulation and other "tracking devices." Study co-author Cesar Hidalgo at Northeastern University promises that researchers didn't know the individuals' phone numbers or identities, and offers that the results are a major advance for science. The study found that people are homebodies -- most stay within 20 miles of their home and are rather habitual. Scientists say the findings -- to be published in Nature on Thursday -- can help improve public transit systems and even fight contagious diseases.