Results for this study are based on telephone interviews conducted by Social Science Research Solutions (SSRS), an independent research company, among a nationally representative sample of 1,375 Latino respondents ages 18 and older, from August 17 through September 19, 2010. Of those respondents, 618 were registered voters. Some 542 respondents were native born (including Puerto Rico), and 833 were foreign born (excluding Puerto Rico). For results based on the total sample, one can say with 95% confidence that the error attributable to sampling is plus or minus 3.3 percentage points.
For this survey, SSRS maintained a staff of Spanish-speaking interviewers who, when contacting a household, were able to offer respondents the option of completing the survey in Spanish or English. A total of 548 respondents were surveyed in English, and 827 respondents were interviewed in Spanish. Any male or female age 18 or older of Latino origin or descent was eligible to complete the survey.
According to government statistics from the National Health Interview Survey (NHIS) during the first six months of 2009, 28% of Hispanic adults lived in households reachable only by cell phone. Adults who are cell-only are very different demographically from those reachable on a landline. In particular, they tend to be younger, less likely to be married or have children, or to own a home. To address the growing number of Hispanic households in the U.S. that are reachable only by cell phone, the study included interviews from both landline (n=710) and cell phone (n=665) sample frames.
Both sample frames were stratified via a disproportionate stratified design. All telephone exchanges in the contiguous 48 states were divided into groups, or strata, based on their concentration of Latino households. For the landline frame, the sample was also run against InfoUSA and other listed databases, and then scrubbed against known Latino surnames. Any “hits” were subdivided into a surname stratum, with all other samples being put into four other RDD strata. The cell phone sample was divided into three strata. Overall, then the study employed eight strata:
It is important to note that the existence of a surname stratum does not mean this was a surname sample design. The sample is RDD, with the randomly selected telephone numbers divided by whether they were found to be associated with or without a Latino surname. This was done simply to increase the number of strata and thereby increase the ability to meet ethnic targets and ease administration by allowing for more effective assignment of interviewers and labor hours.
A five-stage weighting design was used to ensure an accurate representation of the national Hispanic population.
- An adjustment was made for all persons found to possess both a landline and a cell phone, as they were twice as likely to be sampled as were respondents who possessed only one phone type.
- The sample was corrected for the disproportionality of the stratification scheme described earlier.
- The sample was corrected for the likelihood of within-household selection, which depended upon the likelihood that the respondent’s age group would be selected, and that within that age group, the particular respondent would be selected.
- The sample was corrected to reflect the percentage that is cell-only, landline-only, or reachable by either a landline or a cell phone, based upon estimates for Hispanics from the 2009 National Health Interview Survey estimates projected to 2010.
- Finally, the data were put through a post-stratification sample balancing routine. The post-stratification weighting utilized national 2009 estimates from the Census Bureau’s Current Population Survey, March Supplement, on gender, education, age, region, foreign/native born status, year of entry into the U.S., and Hispanic heritage.