The decennial census questionnaire, sent to approximately one in six households for the 1980, 1990, and 2000 censuses, contains all of the questions on the short form, as well as additional detailed questions relating to the social, economic, and housing characteristics of each individual and household. Information derived from the long form is referred to as sample data, and is tabulated for geographic entities as small as the block group level in 1980, 1990, and 2000 census data products. Related terms: Census (decennial), Sample data, Short form