National Survey of Drinking and Driving Attitudes and Behavior: 2008. Volume III: Methodology Report

摘要

This report presents results from the eighth in a series of national telephone surveys conducted for the National Highway Traffic Safety Administration (NHTSA) to assess current status and trends regarding the publics attitudes, knowledge, and self-reported behavior related to drinking and driving. This volume describes the methods used for sampling, data collection, data weighting, data analysis, and also includes copies of the questionnaires. The target population for the 2008 National Survey of Drinking and Driving Attitudes and Behavior was the general driving age public (aged 16 and older) in the 50 States and the District of Columbia. The mode of data collection, as in the previous rounds, was telephone. However, because of the rapidly expanding cell phone only population, as well as to ensure adequate coverage of young adults in the target population, the sample for the 2008 study also included interviews with respondents who use only cell phones and do not have a landline phone in their household. All interviews were conducted in both English and Spanish. The target population was geographically stratified into the four census regions (Northeast, Midwest, South, and West), and sampling was done independently within each stratum (region). The sample allocation across the four regions was proportional to the size of the target population in each region. This is a departure from the NHTSA 2004 and 1999/2000 surveys, where about 100 interviews were completed for each of the 50 States and D.C. Interviewing took place over a three-month period, from September 10, 2008 to December 22, 2008 and each interview averaged about 17.5 minutes in length. For the main study, a total of 50,448 landline and 32,049 cell phone numbers were dialed across all four regions. A total of 6,999 interviews were completed, including 1,607 (about 23%) interviews from the cell phone only sample. A minimum of seven plus seven call design was used to make a human contact and then to complete an interview, and the overall response rate was 24.1%. The procedure for response rate calculation was based on the standard guidelines established by the American Association for Public Opinion Research (AAPOR). The final telephone sample of persons aged 16 and older was weighted to U.S. population counts to account for the sample design, differential non-response, and under-coverage of some groups in the sample frame. For post-stratification weighting, target data were obtained from the Current Population Survey (March 2008).