{"id":184784,"date":"2024-08-14T14:30:17","date_gmt":"2024-08-14T18:30:21","guid":{"rendered":"https:\/\/alpha.pewresearch.org\/pewresearch-org\/?p=184784"},"modified":"2025-08-06T13:18:11","modified_gmt":"2025-08-06T17:18:11","slug":"harris-trump-methodology","status":"publish","type":"post","link":"https:\/\/alpha.pewresearch.org\/pewresearch-org\/politics\/2024\/08\/14\/harris-trump-methodology\/","title":{"rendered":"Methodology"},"content":{"rendered":"\n

Overview<\/h4>\n\n\n\n

Data in this report comes from Wave 151 of the American Trends Panel (ATP), Pew Research Center\u2019s nationally representative panel of randomly selected U.S. adults. The survey was conducted from Aug. 5 to Aug. 11, 2024. A total of 9,201 panelists responded out of 10,079 who were sampled, for a survey-level response rate of 91%.<\/p>\n\n\n\n

The cumulative response rate accounting for nonresponse to the recruitment surveys and attrition is 3%. The break-off rate among panelists who logged on to the survey and completed at least one item is 1%. The margin of sampling error for the full sample of 9,201 respondents is plus or minus 1.3 percentage points.<\/p>\n\n\n\n

SSRS conducted the survey for Pew Research Center via online (n=8,935) and live telephone (n=266) interviewing. Interviews were conducted in both English and Spanish.<\/p>\n\n\n\n

To learn more about the ATP, read \u201cAbout the American Trends Panel.\u201d<\/a><\/p>\n\n\n\n

Longitudinal data<\/h4>\n\n\n\n

A portion of this report utilizes data from a survey that was conducted July 1-7, 2024. To analyze how vote preference may have shifted between July and August, the 8,434 panelists who responded to both surveys were combined and weighted according to the procedures outlined below.<\/p>\n\n\n\n

Panel recruitment<\/h4>\n\n\n\n

Since 2018, the ATP has used address-based sampling (ABS) for recruitment. A study cover letter and a pre-incentive are mailed to a stratified, random sample of households selected from the U.S. Postal Service\u2019s Computerized Delivery Sequence File. This Postal Service file has been estimated to cover 90% to 98% of the population.[1. AAPOR Task Force on Address-based Sampling. 2016. \u201cAAPOR Report: Address-based Sampling.\u201d<\/a>] Within each sampled household, the adult with the next birthday is selected to participate. Other details of the ABS recruitment protocol have changed over time but are available upon request.[2. Email pewsurveys@pewresearch.org<\/a>.] Prior to 2018, the ATP was recruited using landline and cellphone random-digit-dial surveys administered in English and Spanish.<\/p>\n\n\n\n

A national sample of U.S. adults has been recruited to the ATP approximately once per year since 2014. In some years, the recruitment has included additional efforts (known as an \u201coversample\u201d) to improve the accuracy of data for underrepresented groups. For example, Hispanic adults, Black adults and Asian adults were oversampled in 2019, 2022 and 2023, respectively.<\/p>\n\n\n\n

Sample design<\/h4>\n\n\n\n

The overall target population for this survey was noninstitutionalized persons ages 18 and older living in the United States. All active panel members were invited to participate in this wave.<\/p>\n\n\n\n

Questionnaire development and testing<\/h4>\n\n\n\n

The questionnaire was developed by Pew Research Center in consultation with SSRS. The web program used for online respondents was rigorously tested on both PC and mobile devices by the SSRS project team and Pew Research Center researchers. The SSRS project team also populated test data that was analyzed in SPSS to ensure the logic and randomizations were working as intended before launching the survey.<\/p>\n\n\n\n

Incentives<\/h4>\n\n\n\n

All respondents were offered a post-paid incentive for their participation. Respondents could choose to receive the post-paid incentive in the form of a check or gift code to Amazon.com.  Incentive amounts ranged from $5 to $20 depending on whether the respondent belongs to a part of the population that is harder or easier to reach. Differential incentive amounts were designed to increase panel survey participation among groups that traditionally have low survey response propensities.<\/p>\n\n\n\n

Data collection protocol<\/h4>\n\n\n\n

The data collection field period for this survey was Aug. 5 to Aug. 11, 2024. Surveys were conducted via self-administered web survey or by live telephone interviewing.<\/p>\n\n\n\n

For panelists who take surveys online:<\/strong>[3. The ATP does not use routers or chains in any part of its online data collection protocol, nor are they used to direct respondents to additional surveys.] Postcard notifications were mailed to a subset on Aug. 5.[4. Postcard notifications for web panelists are sent to 1) panelists who were recruited within the last two years and 2) panelists recruited prior to the last two years who opt to continue receiving postcard notifications.] Survey invitations were sent out in two separate launches: soft launch and full launch. Sixty panelists were included in the soft launch, which began with an initial invitation sent on Aug. 5. All remaining English- and Spanish-speaking sampled online panelists were included in the full launch and were sent an invitation on Aug. 6.<\/p>\n\n\n\n

\"Table<\/a><\/figure>\n\n\n\n

Panelists participating online were sent an email invitation and up to two email reminders if they did not respond to the survey. ATP panelists who consented to SMS messages were sent an SMS invitation with a link to the survey and up to two SMS reminders.<\/p>\n\n\n\n

For panelists who take surveys over the phone with a live interviewer:<\/strong> Prenotification postcards were mailed on July 31, and reminder postcards were mailed on Aug. 5. The CATI soft launch took place on Aug. 5 and involved dialing until a total of three interviews had been completed. CATI panelists receive up to six calls from trained SSRS interviewers. All remaining English- and Spanish-speaking sampled CATI panelist numbers were dialed throughout the remaining field period.<\/p>\n\n\n\n

Data quality checks<\/h4>\n\n\n\n

To ensure high-quality data, Center researchers performed data quality checks to identify any respondents showing patterns of satisficing. This includes checking for whether respondents left questions blank at very high rates or always selected the first or last answer presented. As a result of this checking, 4 ATP respondents were removed from the survey dataset prior to weighting and analysis.<\/p>\n\n\n\n

Weighting<\/h4>\n\n\n\n

The ATP data is weighted in a process that accounts for multiple stages of sampling and nonresponse that occur at different points in the panel survey process. First, each panelist begins with a base weight that reflects their probability of recruitment into the panel. These weights are then calibrated to align with the population benchmarks in the accompanying table to correct for nonresponse to recruitment surveys and panel attrition. If only a subsample of panelists was invited to participate in the wave, this weight is adjusted to account for any differential probabilities of selection.<\/p>\n\n\n\n

Among the panelists who completed the survey, this weight is then calibrated again to align with the population benchmarks identified in the accompanying table. The weight is then trimmed at approximately the 1st and 99th percentiles to reduce the loss in precision stemming from variance in the weights. Sampling errors and tests of statistical significance take into account the effect of weighting.<\/p>\n\n\n\n

\"Table<\/a><\/figure>\n\n\n\n

CORRECTION (8\/23\/24): A previous version of this methodology incorrectly stated that party affiliation x Voter registration was weighted to the 2022 CPS Voting and Registration Supplement. It was actually weighted to the 2020 CPS Voting and Registration Supplement. This typographical error did not affect the report\u2019s substantive findings.<\/em><\/p>\n\n\n\n

The following table shows the unweighted sample sizes and the error attributable to sampling that would be expected at the 95% level of confidence for different groups in the survey.<\/p>\n\n\n\n

\"Table<\/a><\/figure>\n\n\n\n

Sample sizes and sampling errors for other 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.<\/p>\n\n\n\n

Dispositions and response rates<\/h4>\n\n\n\n
\"Table<\/a><\/figure>\n\n\n\n
\"Table<\/a><\/figure>\n\n\n\n

Validated voters<\/h3>\n\n\n\n

Members of Pew Research Center\u2019s nationally representative American Trends Panel were matched to public voting records from national commercial voter files in an attempt to find records for voting in the 2016 and 2020 general elections. Validated voters<\/strong> are citizens who told us in a post-election survey that they voted in a given election and<\/em> have a record for voting in that election in a commercial voter file. Nonvoters<\/strong> are citizens who were not found to have a record of voting in any of the voter files or told us they did not vote.<\/p>\n\n\n\n

In an effort to accurately locate official voting records, up to three commercial voter files were searched for each panelist. The number of commercial files consulted varied by when a panelist was recruited to the ATP. Three files were used for panelists recruited in 2022 or before, while one file was used for panelists recruited in 2023. Altogether, files from four different vendors were used, including two that serve conservative and Republican organizations and campaigns, one that serves progressive and Democratic organizations and campaigns, and one that is nonpartisan.<\/p>\n\n\n\n

Additional details and caveats about the validation of votes in 2016 and 2020 can be found in these methodological reports:<\/p>\n\n\n\n