Since the early 1970s, the U.S. Census Bureau has conducted the Survey of Market Absorption (SOMA) for the U.S. Department of Housing and Urban Development (HUD). The survey provides vital data measuring how quickly privately financed, nonsubsidized, unfurnished units in buildings with five or more units were rented or sold (absorbed) after completion. Published data are used by builders, banks, market analysts, land planners, and government officials trying to measure the need for federal, state, and local assistance in providing better housing for everyone.

Each month, a sample of residential buildings containing five or more units is created using data collected from the Census Bureau's Survey of Construction which identifies newly built housing units eligible for inclusion in the SOMA. (Beginning in 2002, the survey began collecting information on "Senior Housing" as well.) Units in the SOMA sample receive one to four visits by a field representative. The initial interview, conducted 3 months after the housing unit is identified, collects information on amenities, rent or sales price levels, number of units, type of building, and the number of units taken off the market (absorbed). Field representatives may conduct subsequent interviews (if the units have not been "absorbed") 6, 9, and 12 months after completion.