one-sixth of housing units overall (17 percent, or about 18 million housing units), although sampling rates varied from 13 to 50 percent depending on the population size of the area. Estimates from the long-form sample were released for areas as small as census tracts and block groups. Estimates for the entire population from the data collected for everyone were released at the individual block level, but this was not the case for long-form-sample estimates, both because the estimates were not sufficiently precise at that level and out of concern to protect individual confidentiality.
The long-form questions have changed over time to reflect changing needs for small-area data to implement federal legislation and administer federal programs. In addition to the basic items asked on the short form and depending on how one counts items with multiple parts, the 2000 census long form included 54 sample items about people, covering such topics as marital status, educational attainment, place of birth, citizenship, language spoken at home, English proficiency, ancestry, military service, year moved into residence, various types of disability, responsibility for grandchildren in the home, current and prior year employment status, occupation and industry, transportation to work, and income by type. The 2000 census long form also included 30 sample items about housing, covering such topics as market value of owned home, rent, cost of utilities, characteristics of house or apartment, year structure built, ownership finances, and number of vehicles.
These data have been used by the federal government for such purposes as implementation of sections of the Voting Rights Act, allocation of billions of dollars of federal funds to states and localities, assessment of charges of employment discrimination, and planning, monitoring, and evaluating federal programs. They have also been used by state and local governments for fund allocation, program planning and evaluation, facility planning, and economic development and marketing. Private-sector organizations (retail establishments, restaurants, banks, advertising firms, utility companies, health care providers, etc.) have used long-form-sample data for site location, the targeting of advertising and services, workforce development, and the assessment of compliance with government requirements. Finally, researchers have used long-form-sample data to help understand key social processes, such as internal migration and the correlates of poverty (see National Research Council, 2004b:Ch. 2; National Research Council, 1995:Apps. C, D, E, F, G, H, M, for details).
On one hand, the paired strategy used in modern censuses through 2000 of embedding a long-form sample in the basic decennial census had at least three advantages compared with using a separate survey to collect