Interview and residence rules define the scope of data collection by identifying the types of places included in a survey’s sampling frame and the people eligible for inclusion. The ACS collects information about the population living in both housing units and group quarters, and its residence rules identify who should be interviewed at a sample address. Like the decennial census, the ACS interviews the population without regard to legal status or citizenship and excludes people only if the residence rules define their residence as somewhere other than the sample address.
The ACS uses a rule based on current residence. The people interviewed in an ACS sample housing unit are those who are living or staying in the unit when it is contacted, unless they are staying for only a short time, defined to be two months or less. In general, these short-term occupants are not eligible to be interviewed. Everyone residing in a group quarters when the facility is sampled and visited by an ACS interviewer is considered a resident and is eligible to be interviewed. In contrast, the decennial census determines a principal, or usual, place of residence on April 1, census day, defined as the place where a person lives most of the time.
From American Community Survey: Methodology by Susan Love and Deborah Griffin