Interviewing for the survey was conducted by telephone March 8-28, 2006 among a sample of 1,503 adults age 18 and older. Of these, 1,286 were cell phone users. Approximately half of the interviews (752) were conducted using a landline number frame, with the remainder conducted from a cell phone number frame (751). Both sampling frames were designed by Survey Sampling, Inc. In order to compensate respondents for any toll charges incurred, those interviewed from the cell phone frame were offered an incentive of $10 for completing the survey. Interviewing was conducted by the research firm Schulman, Ronca & Bucuvalas, Inc (SRBI). The samples were prepared by Survey Sampling, Inc.
The data were weighted using demographic weighting parameters derived from the March 2005 Census Bureau’s Current Population Survey, along with estimates of current patterns of telephone status in the U.S., using an iterative technique that simultaneously balances the distributions of all weighting parameters.
Sampling errors for the survey are reported in the sample size table on the next page. 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.