2020 Methodology

The 2020 American Values Atlas (AVA) is a project of PRRI. Results for all demographic, religious affiliation, and political affiliation questions were based on 50,334 bilingual telephone interviews (including 35,212 cell phone interviews) conducted between January 7, 2020 and December 20, 2020 by professional interviewers under the direction of SSRS. National results for questions on specific issues are based on a subset of 10,052 telephone interviews (including 6,981 cell phone interviews) conducted in 10 weeks spread across the year. State level results for questions on specific issues are based on the national subset plus an oversample of 10 key states in 30 additional weeks, resulting in 23,536 interviews across all 50 states plus the District of Columbia (including 16,848 cell phone interviews). Key states include Arizona, California, Florida, Georgia, Michigan, North Carolina, New Mexico, Ohio, Texas, and Utah. The survey was made possible by generous support from the Arcus Foundation, the Evelyn and Walter Haas, Jr. Fund, the Gill Foundation, and Unitarian Universalist Veatch Program at Shelter Rock.

Throughout 2020, at least 1,000 interviews were completed each week, with about 700 interviews conducted among respondents on their cell phones. Mid-year, the cell phone proportion was increased to about 700 per week. Each week, interviewing occurred over a five- or six-day period, starting Tuesdays or Wednesdays and going through Sunday or Monday. The selection of respondents within households was accomplished by randomly requesting to speak with the youngest adult male or female currently living in the household.

Data collection was based on stratified, single-stage, random-digit-dialing (RDD) of landline telephone households and randomly generated cell phone numbers. The sample was designed to represent the total U.S. adult population from all 50 states, including Hawaii and Alaska, and the District of Columbia. The landline and cell phone samples were provided by Marketing Systems Group.

The weighting was accomplished in two separate stages. The first stage of weighting corrects for different probabilities of selection associated with the number of adults in each household and each respondent’s telephone usage patterns. In the second stage, sample demographics were balanced to match target population parameters for gender, age, education, race and Hispanic ethnicity, region (U.S. Census definitions), population density, and telephone usage. The population density parameter was derived from 2010 Census data. The telephone usage parameter came from an analysis of the January-June 2018 National Health Interview Survey. All other weighting parameters were derived from an analysis of the U.S. Census Bureau’s March 2018 Current Population Survey.

The sample weighting was accomplished using iterative proportional fitting (IFP), a process that simultaneously balances the distributions of all variables. Weights are trimmed so that they do not exceed 4.0 or fall below 0.25 to prevent individual interviews from having too much influence on the final results. The use of these weights in statistical analysis ensures that the demographic characteristics of the sample closely approximate the demographic characteristics of the target populations.

The table below shows the sample sizes for all 50 states for both sample and issue subsample. The margin of error for the total sample is +/- 0.5 percentage points at the 95% level of confidence. The margin of error for the national issue subsample is +/- 1.1 percentage points at the 95% level of confidence. The design effect of 1.3 is included in the margins of error. In addition to sampling error, surveys may also be subject to error or bias due to question wording, context, and order effects.

Sample Sizes for the United States

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Sample Sizes for Individual States

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Sample Sizes for Metropolitan Areas