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Sample adult flag

Codes and Frequencies

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ASTATFLG identifies the record of a sample adult. A sample adult is the one adult per family who was selected at random by the computerized survey instrument to answer additional health-related questions, under the survey design instituted in 1997. All persons other than sample adults (those not having the value 1 in ASTATFLG) are coded as "not in universe" for variables derived from the additional questions asked only of sample adults. (Some additional questions were asked of both sample adults and sample children.) Every adult in each family, except for active duty armed forces members, was eligible to be selected as the sample adult.

ASTATFLG has the value "no one selected as sample adult" (code 4) for all adults in the family in the following two cases: 1) sample adult status was incorrectly assigned to someone in the armed forces, or 2) it could not be ascertained which adult in the family was chosen as sample adult.

A similar flag variable, CSTATFLG, identifies the record of a sample child, that is, the one person under 18 per family who was selected at random for additional health-related questions, beginning in 1997, for families that included children.

This variable is automatically included in all extracts, but only has valid values for 1997 forward.


This variable is comparable over time from 1997 to 2004. Prior to 2005, "adult" status was uniformly defined as being age 18 or older. Beginning in 2005, the recognized age of adulthood for defining sample adults varied by state of residence. As the Field Representative's Manual for 2006 explains:

A sample adult is randomly selected by the computer from each family with a household member equal to or greater than the age of majority for a given state and asked more detailed health related questions. In most states this age is 18 years old, but in Alabama and Nebraska this age is 19 and in Mississippi it is 21.

For 2005 forward, persons age 18 in Alabama and Nebraska would be coded "not in universe" (IPUMS NHIS code 0) for ASTATFLG, as would persons age 18, 19, and 20 in Mississippi.


  • 1997-2013; 2014 2015 2016 2017 2018: Persons age 18+.


  • 1997-2018