Gallup US Payroll to Population

Gallup's Payroll to Population results are based on telephone interviews conducted as part of Gallup Daily tracking from June 1-30 for each year -- 2010, 2011, 2012, and 2013 -- with a random sample of approximately 30,000 adults, aged 18 and older, living in all 50 U.S. states and the District of Columbia, selected using random-digit-dial sampling.

For results based on the total sample of national adults, one can say with 95% confidence that the maximum margin of sampling error is ±1 percentage point.

Interviews are conducted with respondents on land-line telephones and cellular phones, with interviews conducted in Spanish for respondents who are primarily Spanish-speaking. Each sample of national adults includes a minimum quota of 50% cellphone respondents and 50% land-line respondents, with additional minimum quotas by region. Land-line telephone numbers are chosen at random among listed telephone numbers. Cellphone numbers are selected using random digit dial methods. Land-line respondents are chosen at random within each household on the basis of which member had the most recent birthday.

Samples are weighted to correct for unequal selection probability, non-response, and double coverage of land-line and cell users in the two sampling frames. They are also weighted to match the national demographics of gender, age, race, Hispanic ethnicity, education, region, population density, and phone status (cellphone only/land-line only/both, cellphone mostly, and having an unlisted land-line number). Demographic weighting targets are based on the March 2012 Current Population Survey figures for the aged 18 and older U.S. population. Phone status targets are based on the July-December 2011 National Health Interview Survey. Population density targets are based on the 2010 census. All reported margins of sampling error include the computed design effects for weighting.

In addition to sampling error, question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of public opinion polls.