location of the users within the dataset. Notably, the dataset does not contain information regarding text messages (SMS) or data usage (internet). More details about the dataset can be found in Text S1. Text S1 (PDF) Text S2 (PDF) Supporting Information Dataset. Home and work location determination. Text S3 Co-location places, geography and communi- cation strength. (PDF) Text S4 (PDF) References Statistical analysis. 1. Albertson LA (1977) Telecommunications as a travel substitute: Some psychological, organizational, and social aspects. Journal of Communication 27: 32–43. 2. Cairncross F (1997) The death of distance Harvard Business School Press. 3. Mitchell WJ (1996) City of bits: space, place, and the infobahn MIT Press. 4. Mokhtarian PL (2003) Telecommunications and travel: The case for complementarity. Journal of Industrial Ecology 6: 43–57. 5. Mok D, Wellman B, Carrasco J (2010) Does distance matter in the age of the internet? Urban Studies 47: 2747–2783. 6. 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PLoS ONE | www.plosone.org 6 July 2011 | Volume 6 | Issue 7 | e20814