Much of the analysis in this report is based on telephone interviews conducted December 13-16, 2012, among a national sample of 1,006 adults 18 years of age or older living in the continental United States (601 respondents were interviewed on a landline telephone, and 405 were interviewed on a cell phone, including 191 who had no landline telephone). Questions about the shooting at an elementary school in Connecticut were added on Friday and were answered by a smaller number of respondents (see table below.) The survey was conducted by interviewers at Princeton Data Source under the direction of Princeton Survey Research Associates International. A combination of landline and cell phone random digit dial samples were used; both samples were provided by Survey Sampling International. Interviews were conducted in English. Respondents in the landline sample were selected by randomly asking for the youngest adult male or female who is now at home. Interviews in the cell sample were conducted with the person who answered the phone, if that person was an adult 18 years of age or older. For detailed information about our survey methodology, see: https://www.pewresearch.org/politics/methodology/.
The combined landline and cell phone sample are weighted using an iterative technique that matches gender, age, education, race, Hispanic origin and region to parameters from the March 2011 Census Bureau’s Current Population Survey and population density to parameters from the Decennial Census. The sample also is weighted to match current patterns of telephone status, based on extrapolations from the 2011 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 among respondents with a landline phone. Sampling errors and statistical tests of significance take into account the effect of weighting. The following table shows the unweighted sample sizes and 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.
Some of the analysis in this report is based on survey data collected by Google among a sample of internet users. The survey questions were asked December 14-17, 2012 among a sample of about 800 adults with school age children using Google Consumer Surveys. The Google Consumer Surveys method has the ability to capture reactions from a broadly representative, though non-probability, sample of internet users in a relatively short period of time. Internet users are sampled by selecting a stratified sample of people visiting the websites of a diverse group of about 100 publishers that allow Google to ask one or two questions of visitors to their site. This sampling procedure is different from other internet surveys that rely on people who “opt-in” to participate or that randomly survey respondents who have agreed to be part of a pre-recruited online panel.
The data are weighted to match national parameters for internet users on age, gender and region or state; these demographic characteristics are inferred based on the types of websites the users visit as recorded in their DoubleClick advertising cookie and their computer’s internet address. Because the final sample is not a probability sample of all internet users, it cannot be assigned a margin of sampling error.
Because only two questions can be asked of any individual respondent, these questions were asked as two separate surveys. For each survey, adults with school age children in the household were first identified using a screening question and then were asked the question about the Connecticut shootings. The response rate for the initial question screening for parents was 26-28% and the response rate to the follow-up question was 59-62% among the adults with children identified in the screener. There are limited demographic variables (only inferred age, gender, location and income) available for analysis than from traditional survey questionnaires. More on the Google Consumer Survey Methodology is available here.
Question wording and full results are available in the topline, including links to the surveys on the Google Consumer Surveys site.