Methods
The Pew Research Center Library Survey, sponsored by the Pew Research Center’s Internet & American Life Project and the Gates Foundation, obtained telephone interviews with a nationally representative sample of 6,224 people ages 16 and older living in the United States. Interviews were conducted via landline (nLL=3,122) and cell phone (nC=3,102, including 1,588 without a landline phone). The survey was conducted by Princeton Survey Research Associates International. The interviews were administered in English and Spanish by Princeton Data Source from July 18 to September 30, 2013 . Statistical results are weighted to correct known demographic discrepancies. The margin of sampling error for results based on the complete set of weighted data is ±1.4 percentage points. Results based on the 5,320 internet users have a margin of sampling error of ±1.5 percentage points.