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Glossary and Description of Census Programs

For more information, go to the American FactFinder site and click on glossary.

American Community Survey (ACS)
The American Community Survey is a large, continuous demographic survey conducted by the Census Bureau that will eventually provide accurate and up-to-date profiles of America's communities every year. The survey produces annual and multi-year estimates of population and housing.

American FactFinder (AFF)
An electronic system for access and dissemination of Census Bureau data on the Internet.

Refers to a person's self-identification of heritage, ethnic origin, descent, or close identification to an ethnic group.

The number found by dividing the sum of all quantities by the total number of quantities.

Average family size
A measure obtained by dividing the number of members of families by the total number of families (or family householders).

Average household size
A measure obtained by dividing the number of people in households by the total number of households (or householders).

A subdivision of a census tract. A block is the smallest geographic unit for which the Census Bureau tabulates 100-percent data. Over 8 million blocks are identified for Census 2000.

Block group (BG)
A subdivision of a census tract. A block group is the smallest geographic unit for which the Census Bureau tabulates sample data. A block group consists of all the blocks within a census tract with the same beginning number.

A complete enumeration, usually of a population, but also of businesses and commercial establishments, farms, governments, and so forth.

A type of incorporated place in 49 states and the District of Columbia.

Confidence interval (American Community Survey)
The sample estimate and its standard error permit the construction of a confidence interval that represents the degree of uncertainty about the estimate. Each American Community Survey and Census 2000 Supplementary Survey estimate is accompanied by the upper and lower bounds of the 90 percent confidence interval, which can be interpreted roughly as providing 90 percent certainty that the true number falls between the upper and lower bounds.

Decennial Census
The census of population and housing, taken by the Census Bureau in years ending in 0 (zero). Article I of the Constitution requires that a census be taken every ten years for the purpose of reapportioning the U.S. House of Representatives.

Economic Census
Collective name for the censuses of construction, manufactures, minerals, minority- and women-owned businesses, retail trade, service industries, transportation, and wholesale trade, conducted by the Census Bureau every five years, in years ending in 2 and 7.

Employed includes all civilians 16 years old and over who were either (1) "at work" -- those who did any work at all during the reference week as paid employees, worked in their own business or profession, worked on their own farm, or worked 15 hours or more as unpaid workers on a family farm or in a family business; or (2) were "with a job but not at work" -- those who did not work during the reference week but had jobs or businesses from which they were temporarily absent due to illness, bad weather, industrial dispute, vacation, or other personal reasons.

Estimates (American Community Survey and Census 2000 Supplementary Survey)
Data for the American Community Survey and Census 2000 Supplementary Survey are collected from a sample of housing units and used to produce estimates of the actual figures that would have been obtained by interviewing the entire population using the same methodology.

Family household (Family)
A family includes a householder and one or more people living in the same household who are related to the householder by birth, marriage, or adoption. All people in a household who are related to the householder are regarded as members of his or her family. A family household may contain people not related to the householder, but those people are not included as part of the householder's family in census tabulations.

Group quarters (GQ)
The Census Bureau classifies all people not living in households as living in group quarters. There are two types of group quarters: institutional (for example, correctional facilities, nursing homes, and mental hospitals) and non-institutional (for example, college dormitories, military barracks, group homes, missions, and shelters).

Hispanic or Latino origin
For Census 2000, American Community Survey: People who identify with the terms "Hispanic" or "Latino" are those who classify themselves in one of the specific Hispanic or Latino categories listed on the Census 2000 or ACS questionnaire - "Mexican," "Puerto Rican," or "Cuban" - as well as those who indicate that they are "other Spanish, Hispanic, or Latino." Origin can be viewed as the heritage, nationality group, lineage, or country of birth of the person or the person's parents or ancestors before their arrival in the United States. People who identify their origin as Spanish, Hispanic, or Latino may be of any race.

A household includes all the people who occupy a housing unit as their usual place of residence.

Household size
The total number of people living in a housing unit.

Housing unit
A house, an apartment, a mobile home or trailer, a group of rooms, or a single room occupied as separate living quarters, or if vacant, intended for occupancy as separate living quarters.

Lower bound (American Community Survey)
Represents the low end of the 90 percent confidence interval of an estimate from a sample survey.

Margin of error (MOE)
A margin of error is the difference between an estimate and its upper or lower confidence bounds. All published margins of error for the American Community Survey are based on a 90 percent confidence level.

This measure represents an arithmetic average of a set of numbers.

Mean income
Mean income is the amount obtained by dividing the total income of a particular statistical universe by the number of units in that universe. Thus, mean household income is obtained by dividing total household income by the total number of households. For the various types of income, the means are based on households having those types of income.

This measure represents the middle value (if “n” is odd) or the average of the two middle values (if “n” is even) in an ordered list of data values. The median divides the total frequency distribution into two equal parts: one-half of the cases fall below the median and one-half of the cases exceed the median.

Median age
This measure divides the age distribution in a stated area into two equal parts: one-half of the population falling below the median value and one-half above the median value.

Median income
The median income divides the income distribution into two equal groups, one having incomes above the median, and the other having incomes below the median.

Occupied housing unit
A housing unit is classified as occupied if it is the usual place of residence of the person or group of people living in it at the time of enumeration.

Per capita income
Average obtained by dividing aggregate income by total population of an area.

All people, male and female, child and adult, living in a given geographic area.

Population density
Total population within a geographic entity (for example, United States, state, county, place) divided by the land area of that entity measured in square kilometers or square miles.

Population estimate (Population Estimates Program)
The Census Bureau's Population Estimates Program (PEP) produces July 1 estimates for years after the last published decennial census (2000). PEP estimates are used in federal funding allocations, in setting the levels of national surveys, and in monitoring recent demographic changes.

Population projections
Estimates of the population for future dates. They illustrate plausible courses of future population change based on assumptions about future births, deaths, international migration, and domestic migration. For more information:

Following the Office of Management and Budget's (OMB's) Directive 14, the Census Bureau uses a set of money income thresholds that vary by family size and composition to detect who is poor.

Race is a self-identification data item in which respondents choose the race or races with which they most closely identify.

Standard deviation
A measure which shows the average variability in population from the mean. It is defined as the square root of the variance.

Standard error (ACS)
The standard error is a measure of the deviation of a sample estimate from the average of all possible samples.

State data center (SDC)
A state agency or university facility identified by the governor of each state and state equivalent to participate in the Census Bureau's cooperative network for the dissemination of census data. An SDC also may provide demographic data to local agencies participating in our statistical areas.

All civilians 16 years old and over are classified as unemployed if they (1) were neither "at work" nor "with a job but not at work" during the reference week; and (2) were actively looking for work during the last 4 weeks; and (3) were available to accept a job. Also included as unemployed are civilians who did not work at all during the reference week, were waiting to be called back to a job from which they had been laid off, and were available for work except for temporary illness.

Upper bound (American Community Survey)
Represents the high end of the 90 percent confidence interval of an estimate from a sample survey.

|     Last modified: Jun 05, 2012