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Who is included in NSDUH estimates? How are they chosen?

NSDUH samples all people living in the United States who are:

  • Age 12 or older,
  • Not living in institutions such as prisons or nursing homes,
  • Not military personnel on active duty,
  • Not experiencing homelessness with no fixed address, and
  • Able to answer the questionnaire in either English or Spanish.

More information on data collection is available from the annual Data Collection Final Report.

NSDUH is conducted using stratified sampling with multiple levels of selection. Households are chosen geographically. That means that a particular area is randomly selected, and then households are selected within that area. Basic information is first collected from selected households, and then 0, 1, or 2 members of the household are chosen to complete the full survey. Respondents are chosen so that about a quarter are age 12 to 17, another quarter are age 18 to 25, 15 percent are age 26 to 34, 20 percent age 35 to 49, and 15 percent age 50 or older.

The geographic selection process is complex. The United States is first broken up into 750 sub-state regions that do not cross state lines and have roughly equal populations. From each of these regions, census tracts or collections of tracts are chosen using systematic sampling. Tracts are sorted by socioeconomic status, urban area, percent of the population that is White, and percent of the population that is Hispanic before they are systematically selected. This ensures a broad variety of census tract types are chosen.

Within each census tract or tracts, a “segment” of adjacent block groups or blocks are randomly selected. Segments are formed to contain a minimum of 150 or 250 dwelling units (DUs) in urban areas, and 100 or 200 DUs in rural areas, depending on the state. Eight segments are chosen for interviewing in each of the 750 regions every year.

More detail on sampling procedures, including changes that have been made over the past two decades, can be found in the annual NSDUH Sample Design Report.

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