When information is missing or inconsistent, the Census Bureau uses a method called imputation to assign values. Imputation relies on the statistical principle of "homogeneity," or the tendency of households within a small geographic area to be similar in most characteristics. For example, the value of "rented" is likely to be imputed for a housing unit not reporting on owner/renter status in a neighborhood with multiunits or apartments where other respondents reported "rented" on the census questionnaire. In past censuses, when the occupancy status or the number of residents was not known for a housing unit, this information was imputed.

Summary File 3 (SF 3) contains the sample data, which is the information compiled from the questions asked of a sample of all people and housing units. Population items include basic population totals; urban and rural; households and families; marital status; grandparents as caregivers; language and ability to speak English; ancestry; place of birth, citizenship status, and year of entry; migration; place of work; journey to work (commuting); school enrollment and educational attainment; veteran status; disability; employment status; industry, occupation, and class of worker; income; and poverty status. Housing items include basic housing totals; urban and rural; number of rooms; number of bedrooms; year moved into unit; household size and occupants per room; units in structure; year structure built; heating fuel; telephone service; plumbing and kitchen facilities; vehicles available; value of home; monthly rent; and shelter costs.

In Summary File 3, population tables are identified with a "P" and housing tables are identified with an "H" prefix, followed by a sequential number. The "P" and "H" tables are shown for the block group and higher levels of geography, while the "PCT" and "HCT" tables are shown for the census tract and higher levels of geography. There are 16 "P" tables, 15 "PCT" tables, and 20 "HCT" tables that bear an alphabetic suffix on the table number, indicating that they are repeated for nine major race and Hispanic or Latino groups.¹

Summary File 3 contains a total of 813 unique tables-484 population tables and 329 housing tables. The chart below summarizes the geographic coverage available for the tables and the tables that are repeated by race and Hispanic or Latino.



¹These selected tables are repeated by the following: White alone; Black or African American alone; American Indian and Alaska Native alone; Asian alone; Native Hawaiian and Other Pacific Islander alone; Some other race alone; Two or more races; Hispanic or Latino; and White alone, not Hispanic or Latino.

Tables are shown	Population tables (484)	Housing tables (329)
To the block group and higher	P1 through P160	H1 through H121
By race and Hispanic or Latino, with alphabetic suffix A-I	P145 through P160 (e.g., P145A, P145B, P145C, ..., P145I, etc.)	None
To the census tract level and higher	PCT1 through PCT76	HCT1 through HCT48
By race and Hispanic or Latino, with alphabetic suffix A-I	PCT62 through PCT76 (e.g., PCT62A, PCT62B, PCT62C, ..., PCT62I, etc.)	HCT29 through HCT48 (e.g., HCT29A, HCT29B, HCT29C, ..., HCT29I, etc.)

SF 3 includes population and housing characteristics for the total population and for a limited list of race and Hispanic or Latino groups. Population and housing items may be cross tabulated. Selected aggregates and medians also are provided. A complete listing of subjects in this file is found in the section, "Subject Locator."