Hampton, K.N., L.S. Goulet, L. Rainie, and K. Purcell, Why Most Facebook Users Get More Than They Give. Pew Research: Washington, D.C., February 3, 2012.
From the report: "Half the adults and three-quarters of the teenagers in America use social networking sites (SNS) and Facebook by far is the most popular of these sites. The Pew Research Center’s Internet & American Life Project fielded a nationally representative phone survey about the social and civic lives of SNS users and reported the findings in June 2011 in a report entitled “Social networking sites and our lives.” During the phone survey, 269 of 877 original respondents who were Facebook users gave us permission to access data on their use of Facebook so that it could be matched with their survey responses. We partnered with Facebook to match individual responses from the survey with profile information and computer logs of how those same people used Facebook services over a one-month period in November 2010 that overlapped when the survey was in the field. The results of that special analysis of 269 Facebook users identified in and recruited from a random, representative telephone survey are reported here." Read more