Figure 2.

The location (after adding randomized synthetic noise) of several hundred mobile devices in the city of San Francisco. Each location is color coded to indicate which of 8 “tribes” (or social clusters) each user belongs to. Tribes are computed by clustering (otherwise anonymized) users according to how similar their movement patterns are over a few weeks. The movement analysis is performed using the Minimum Volume Embedding algorithm (7, 8, 24)