The Congressional Connection Poll is a collaboration of the Pew Research Center for the People & the Press and the National Journal, sponsored by (SHRM) the Society for Human Resource Management. The survey will be conducted weekly when Congress is in session, and each week’s survey will focus on themes and issues related to Congress and the political process.
Results for this survey are based on telephone interviews conducted under the direction of Princeton Survey Research Associates International among a national sample of 1,001 adults living in the continental United States, 18 years of age or older, from July 8-11, 2010 (670 respondents were interviewed on a landline telephone, and 331 were interviewed on a cell phone, including 123 who had no landline telephone). Both the landline and cell phone samples were provided by Survey Sampling International. Interviews were conducted in English.
The combined landline and cell phone sample are weighted using an iterative technique that matches gender, age, education, race, Hispanic origin, region, and population density to parameters from the March 2009 Census Bureau’s Current Population Survey. The sample is also weighted to match current patterns of telephone status, based on extrapolations from the 2009 National Health Interview Survey. The weighting procedure also accounts for the fact that respondents with both landline and cell phones have a greater probability of being included in the combined sample and adjusts for household size within the landline sample. Sampling errors and statistical tests of significance take into account the effect of weighting.
The following table shows the error attributable to sampling that would be expected at the 95% level of confidence for different groups in the survey:
In addition to sampling error, one should bear in mind that question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of opinion polls.