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National Public Opinion Reference Survey, 2020




Ipsos conducted the National Public Opinion Reference Survey (NPORS) for the Pew Research Center using address-based sampling and a push-to-web protocol. The survey was fielded June 1, 2020, to August 11, 2020. Participants were first mailed an invitation to complete an online survey. A paper survey was later mailed to a large subset (79%) of those who did not respond. In total, 1,862 respondents completed the survey online and 2,246 respondents completed the paper survey. The survey was administered in English and Spanish.

The ARDA has added four additional variables to the original data set to enhance the users' experience on our site.

Data File

Cases: 4108
Variables: 61

The survey was weighted to support reliable inference from the sample to the target population of U.S. adults. The weight was created using a multistep process that includes a base weight adjusting for differential probabilities of selection and a raking calibration that aligns the survey with the population benchmarks. The process starts with the base weight, which accounted for the probability of selection of the address from the U.S. Postal Service Computerized Delivery Sequence File frame, as well as the number of adults living in the household. Then the base weights are calibrated to population benchmarks using raking, or iterative proportional fitting. The raking dimensions and the source for the population parameter estimates are reported in the table below. All raking targets are based on the non-institutionalized U.S. adult population (ages 18 and older). These weights are trimmed at about the 1st and 99th percentiles to reduce the loss in precision stemming from variance in the weights.

Data Collection

June 1 - August 11, 2020

Original Survey (Instrument)

2020 National Public Opinion Reference Survey Paper
2020 National Public Opinion Reference Survey Online

Funded By

Pew Research Center

Collection Procedures

Mailing protocol
Ipsos sent initial mailings in a 9-by-12-inch envelope via first class mail to the 14,387 sampled households. These packets included two $1 bills and a letter asking a member of the household to complete an online survey using the website and password provided. If two or more adults were in the household, the letter asked the adult with the next birthday to complete the survey. Sampled households were later sent a reminder postcard and then a reminder letter via first class mail.

In total 12,670 households did not respond to the online survey invitation but were deliverable addresses. A random 10,000 of these nonresponding households (79%) were selected for the paper survey stage and were sent a letter, $5 bill, paper version of the survey and a postage-paid return envelope via mail. The paper survey was one 11-by-17-inch page folded booklet-style. The within household selection instructions were identical to those used in the earlier online survey request. These households were later sent a reminder postcard.

Households in Hispanic strata received all materials in English and Spanish. All other households received materials in English only. Those who completed the survey online or returned the completed paper survey were sent a $10 post-incentive.

Sampling Procedures

The sample was drawn from the U.S. Postal Service Computerized Delivery Sequence File (DSF) and was provided by MSG (Marketing Systems Group). Occupied residential addresses (including 'drop points') in all U.S. states (including Alaska and Hawaii) and the District of Columbia had a nonzero chance of selection. The draw was a national, stratified random sample, with differential probabilities of selection across the mutually exclusive strata. Ipsos designed the sample plan with the goal of obtaining in the recruited panel the distribution of age-by-race groups shown in the table to the right.

Principal Investigators

The Pew Research Center

Related Publications

Pew Research Center. (2021). "About Three-in-Ten U.S. Adults Are Now Religiously Unaffiliated."

Pew Research Center. (2021). "How Pew Research Center Uses Its National Public Opinion Reference Survey (NPORS)."

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