If someone lives with roommates, how are they counted? E.g. If someone lives with 3 roommates, would they be counted as a non-family household of 4 or a single person? If someone in an apartment share fills out the Census on their own as a “household,” but they have the same address and apartment number as other Census respondents, does the Census collate those responses into a household?
Roommates who share the home and expenses are counted as a single household by the US Census. The variable RELATE describes the individual’s relationship to the head of household; it includes detailed codes (select the radio-button labelled “Detailed Codes”) for relatives and non-relatives living in the household. According to the comparability tab for RELATE, the category for non-relatives has changed over time (see the sub-heading ‘Partner/friend’).
This category changes considerably in meaning across census years. Before 1960, the category “partner” refers to a non-relative who shares the home and expenses with the head, including responses such as co-head and business partner. In 1960 and 1970, the ‘Partner/friend’ value is a residual category for all non-relatives in the household who are not employees or lodgers. In 1980, ‘Partner/roommate’ refers to a non-relative who lives with the householder and shares expenses. In 1990, 2000, and the ACS, this category is split into ‘Housemate or roommate’ and ‘Unmarried partner’–the latter of which is supposed to distinguish those with a “close personal relationship” with the householder (see “spouse,” above).
In reference to your second question, the US Census Bureau encourages residents to complete one form for the entire household. However, if multiple forms are filled out under the same address, the Census Bureau will merge the surveys together; no individuals will be omitted. Please follow up with me if I have misunderstood the variables that you are interested in.