National Health Interview Survey (NHIS) Restricted Variables
If researchers interested in using NHIS data find that something asked on the questionnaires does not have a corresponding variable in the public use data set, that variable may be restricted. The following list is not exhaustive, but it provides examples of NHIS variables that are restricted.
Geography is most often used to add contextual data to NHIS data. The geocodes page lists what geographic codes are available for 1990-current NHIS.
Examples of Restricted Variables Used by Other Researchers
- Country of Birth and Related Immigration Variables (Person File)
- State and Year of Birth (Person File)
- Industry and Occupation Codes (Person File before 1997, Sample Adult 1997-present)
- Detailed Race and Hispanic Origin (Person File)
- Exact Dates (e.g., date of birth in Person File)
Restricted and Public Use Variable Lists *
- 1997_2003 NHIS Variables Sorted By Question_With_IncomeVarsCdc-pdf [PDF – 455 KB]
- 2004-2008 NHIS Variables Sorted by QuestionCdc-pdf [PDF – 564 KB]
- 2009-2013 NHIS Variables Sorted by QuestionCdc-pdf [PDF – 852 KB]
- 2014-2017 NHIS Variables Sorted by Question Cdc-pdf[PDF – 923 KB]
*All lists are sorted by question.
More detailed documentation, such as variable values and questionnaire information, for 1997 to the present are available by request. If you are interested in receiving the documentation, please contact your RDC Analyst or RDCA@cdc.gov. Detailed variable lists are not currently available for earlier years not shown.
In order to find NIS Teen restricted variables, you will need to know the question number from the NIS Teen questionnaire to identify the comparable restricted variables.