2016 validated voters:
Measures of 2016 turnout and vote choice rely on panelists’ responses to questions about voter turnout and candidate preference on American Trends Panel surveys conducted between Nov. 29 – Dec. 12, 2016 and Nov. 7-16, 2018. Self-reported vote choice collected immediately after the election was used for panelists recruited prior to the 2016 election. For panelists recruited after the 2016 election (in the 2017 and 2018 panel recruitments detailed in the methodology statement), a retrospective vote choice measure was collected in 2018.1 Panelists recruited in the 2019 recruitment (and those from the 2018 recruitment who were not eligible to vote in the 2016 elections) were excluded from this part of the analysis.
Panelists’ turnout in 2016 was verified by matching the panelists to commercial voter file databases, which collect official state voting records. Researchers attempted to match panelists who completed the 2016 survey to five commercial voter file databases (see this report for a detailed discussion of how this was accomplished); panelists recruited after 2016 were matched to two commercial voter file databases. Panelists who were verified as having voted in at least one of the commercial voter databases were considered to be validated voters.
2018 validated voters:
To produce estimates of validated 2018 voters, researchers attempted to match responses about voter turnout from an ATP survey conducted just after the election Nov. 7-16, 2018 to two commercial voter file databases. Panelists who were verified as having voted in at least one of the commercial voter file databases were considered to be validated voters. Candidate choice for 2018 verified voters was measured in this post-election survey.
© Pew Research Center, 2020