All persons occupying a single housing unit (see Part III, Housing Concepts) are referred to as a household. Average population per household is calculated as the population in households divided by the number of households. (See also persons per unit in Part III. )

All persons who are not members of households are regarded as living in group quarters. (See Part III, Housing Concepts.)

Quarters occupied by 5 or more persons unrelated to the head of the household are called group quarters. Quarters with no designated head but with 6 or more unrelated persons are also group quarters.

Some quarters occupied by only one or two persons may also be group quarters. For example, one to five persons occupying a surgical ward of a general hospital, who have no usual residence elsewhere, are in group quarters, as are students living in dormitories. Institutional quarters occupied by one or more patients or inmates are institutional group quarters.

All members of group quarters are classified as either secondary individuals or as inmates of institutions. Group quarters members are classified by type of group quarters as shown below.

Persons for whom care or custody is being provided in institutions. Includes inmates of mental hospitals, inmates of homes for the aged, and inmates of other institutions . Census sample basic records include type of institution categories.

Further classified as shown below. (See also secondary individual .)

In addition to rooming and boarding houses, this category includes group quarters in ordinary homes, tourist homes, residential clubs, and Ys. (Not all persons living in these types of quarters are classified as living in group quarters; some are classified as living in housing units. ) (See Concept No. 151.1, housing units.)

Quarters for military personnel which are not divided into separate housing units. In 1960, data on persons in such quarters were shown only for men. In 1970, they will include both men and women as well as being shown separately for men.

Includes dormitories and fraternity and sorority houses.

Includes general hospitals (including quarters for staff), missions or flophouses, ships, religious group quarters such as convents, dormitories for workers (such as logging camps or quarters for migratory workers). In 1960, women in military barracks were also classified as in other group quarters in tabulations. In 1970, resident staff members of institutions (persons occupying group quarters on institutional grounds who provide care or custody for inmates) are classed as in other group quarters in tabulations (but carried separately on census basic records); in 1960, such persons were shown as a separate category.