The AHS collects data on housing units only. The Census Bureau defines a housing unit (HU) as a single-family house, townhouse, mobile home or trailer, apartment, group of rooms, or single room that is occupied as a separate living quarters or, if vacant, is intended for occupancy as separate living quarters. In order to be a HU, the structure must meet the following two requirements—separateness and direct access. Separate living quarters are those in which the occupants live separately from any other persons in the building. Direct access refers to how occupants enter their living quarters. If an occupant or intended occupant must go through another HU to get to the sample unit (SU), then the SU does not have direct access and, therefore, the SU is not a housing unit. Examples of direct access include:
By contrast, the AHS does not collect data on group quarters (GQs). GQs are a type of living quarters where the residents share common facilities or receive authorized care or custody. Units in independent, assisted, or congregate housing are not group quarters if the residents live separately (independently). For more information, see the “Housing units” entry in the AHS Subject Definitions.