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Sample adult flag, longitudinal or partial sample

Codes and Frequencies

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For sample adults, SALNGPRTFLG identifies whether a sample adult was part of the original 2020 partial sample or the 2020 longitudinal sample.

Due to the coronavirus pandemic in 2020, about half of the original NHIS sample allocated for the last five months of 2020 was replaced with persons that completed a Sample Adult interview in the 2019 NHIS. This group of sample adults that completed interviews in the 2019 and 2020 NHIS are referred to as the "longitudinal" sample and the original 2020 respondents are referred to as the "partial" sample. Persons in the longitudinal sample were interviewed for the 2020 NHIS at least 12 months after their initial 2019 interview date. According to the 2020 Survey Description, the longitudinal sample was introduced "due to concerns about possible loss of coverage and lower response rates typically associated with telephone interviewing." See the user note on COVID-related changes to the NHIS for more information. Due to methodological concerns, sample children were not included in the longitudinal sample.


This variable is completely comparable.


  • 2020: Sample adults age 18+.


  • 2020