The analysis in this report is based on telephone interviews conducted Sept. 7-12, 2021, among a national sample of 1,008 adults, 18 years of age or older, living in the United States (201 respondents were interviewed on a landline telephone, and 807 were interviewed on a mobile phone, including 553 who had no landline telephone). The survey was conducted under the direction of SSRS. A combination of landline and mobile phone random-digit-dial samples were used. Interviews were conducted in English (973) and Spanish (35). For detailed information about our survey methodology, see http://www.pewresearch.org/methodology/u-s-survey-research/.
The SSRS Omnibus sample is designed to represent the adult U.S. population. The SSRS Omnibus uses a fully replicated, stratified, single-stage, random-digit-dialing (RDD) sample of landline telephone households, and randomly generated mobile phone numbers. Sample telephone numbers are computer generated and loaded into online sample files accessed directly by the computer-assisted telephone interviewing (CATI) system.
Each SSRS Omnibus insert is weighted to provide nationally representative and projectable estimates of the adult population 18 years of age and older. The weighting process takes into account the disproportionate probabilities of household and respondent selection due to the number of separate telephone landlines and mobile phones answered by respondents and their households, as well as the probability associated with the random selection of an individual household member. Following application of the above weights, the sample is post-stratified and balanced by key demographics: age, race, sex, region and education. The sample is also weighted to reflect the distribution of phone usage in the general population, meaning the proportion of those who are mobile phone only, landline only and mixed users.
The following table shows the unweighted sample size and the error attributable to sampling that would be expected at the 95% level of confidence for different groups in the U.S. in the survey:
Sample sizes and sampling errors for subgroups are available upon request.
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.
German results can be found through Körber-Stiftung.