These findings are based on a combined analysis of two nationally representative telephone surveys (details of each are below). The combined data set contained a total of 2,010 respondents, 346 of whom had made a monetary contribution to any of the presidential candidates in the 2012 election. The margin of sampling error for the complete data set is +/-2.6 percentage points, and the margin of sampling error for presidential campaign contributors is +/-6.3 percentage points.

The PSRAI September 2012 Omnibus Week 3 obtained telephone interviews with a nationally representative sample of 1,005 adults living in the continental United States. Telephone interviews were conducted by landline (605) and cell phone (400, including 211 without a landline phone). The survey was conducted by Princeton Survey Research Associates International (PSRAI). Interviews were done in English by Princeton Data Source from September 20 to 23, 2012. Statistical results are weighted to correct known demographic discrepancies. The margin of sampling error for the complete set of weighted data is ± 3.7 percentage points.

The PSRAI September 2012 Omnibus Week 4 obtained telephone interviews with a nationally representative sample of 1,005 adults living in the continental United States. Telephone interviews were conducted by landline (603) and cell phone (402, including 184 without a landline phone). The survey was conducted by Princeton Survey Research Associates International (PSRAI). Interviews were done in English by Princeton Data Source from September 27 to 30, 2012. Statistical results are weighted to correct known demographic discrepancies. The margin of sampling error for the complete set of weighted data is ± 3.7 percentage points.