Restricted NCHS Variables

Restricted data is information that could compromise the confidentiality of survey respondents or institutions, or is sensitive by nature. To access these variables, a proposal must be approved by the Research Data Center. The following links take you to information about the specific data system. We recognize that these lists are not exhaustive, so if after reviewing this documentation you cannot find the information you are looking for, please email Please refer to these lists when preparing the data dictionary for your RDC proposal.

We encourage researchers to review all of the methodological information (i.e. analytic guidelines and sample design documentation) available about the data before submitting a proposal.