Web data collection across devices: smartphone, tablet, and PC. 2015

We selected address-based samples in each of eight counties around the United States. The counties were selected purposively, based on the availability of experienced field staff there. Still, the set of eight sample counties encompassed a range of different types of areas. Seven were in metropolitan statistical areas and the other was rural; one of the seven metropolitan areas involved a small central city. The eight counties included all four Census regions. Within each county, we selected a full probability sample of addresses. We used Census block groups as the second-stage sampling units (SSUs). Six SSUs were selected from each county with probabilities proportional to size (in housing units). One SSU was on a military base and was replaced with the next SSU in the county. In total, we selected 1,824 addresses, 228 within each sample county and 38 in each sample SSU. One hundred forty-two of the addresses were vacant, could not be found, or turned out not to be dwellings, leaving a final sample of 1,682 occupied dwelling units. When they contacted a household, interviewers tried to complete a short screener with an adult there. In households with just one adult, he or she was selected for the main interview; in households with two adults, one of the two was selected randomly; and, in households with three or more adults, the last birthday method was used to select one for the main interview. Once the sample person had been designated, he or she was asked to complete the interview on a device that had been randomly determined ahead of time. Sample persons were offered a $20 incentive to complete the questionnaire.