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Essential vocabulary


Age data is reported for five-year age groups and select summary groups such as 18 years and over.

Median age

Median age is calculated from the distribution of age by five-year groups. See Median.

American Community Survey (ACS)

In 2010, the Census Bureau changed how it collects decennial census data. The Census Bureau has eliminated the traditional long form and opted to only release decennial census data collected from the short form. The American Community Survey (ACS) is the replacement for census sample data, or long form. Data on income, education, employment, language, migration, citizenship, marital status, and housing characteristics, such as value and rent, is now obtained from the ACS rather than the decennial census sample.

The ACS provides data that is updated more frequently than the decennial census data. The ACS collects and produces population and housing information every year instead of every 10 years. ACS represents continuous measurement or a rolling sample design. A small percent of the population is sampled every month. The monthly samples are combined and averaged to produce one-, three- or five-year databases. The Census 2000 sample represented approximately 1 in 6 households and one point in time, April 1, 2000. ACS represents approximately 1 in 40 households. ACS' much smaller sample sizes affect data reporting and produce much larger sampling errors.

Each ACS estimate is reported with a Margin of Error (MOE). The MOE is a measure of the variability of the estimate due to sampling error. The MOE enables data users to measure the range of uncertainty around each estimate. This range can be calculated with 90 percent confidence by taking the estimate +/- the MOE. For example, if the ACS reports an estimate of 100 +/- 20, then there is a 90 percent chance that the value for the total population falls between 80 and 120. The larger the MOE, the lower the precision of the estimate and the less confidence one should have that the estimate is close to the true population value.

For more information about ACS, see Census and ACS.

Annual compound growth rate

The annual compound growth rate is calculated using the following formula:

formula for calculating annual compund growth rate

where P=Population.

Average household size

See Household.


A census block is a component of a block group identified by a four-digit code. Blocks are small in area, in general, especially in cities. However, blocks in rural or remote areas may cover hundreds of square miles. A block code that starts with a zero indicates a water-only block.

Block group (BG)

A block group is a collection of one or more blocks and a statistical division of a census tract identified by a one-digit code. Block groups do not cross census tract, county, or state boundaries. In general, a block group is comprised of 600 to 3,000 residents. A zero block group code indicates a water-only BG.

Census 2010

The U.S. Census takes place every 10 years. It is mandated by the U.S. constitution and counts every resident in the United States. Census data is used to distribute federal funds to local communities and determine the number of seats each state has in the U.S. House of Representatives. It is used by businesses and local and state governments to analyze the underlying demographics of an area.

Data derived from Census 2010 will be different than data from past years. The most significant change is due to the Census Bureau's omission of the long form. The short census questionnaire provides only the complete counts of population, households, and housing units plus the following characteristics: sex, age, race, Hispanic origin, household relationship, occupancy, and tenure. Every other variable was previously collected from the sample long form. Now, data about income, education, employment, language, migration, citizenship, marital status, and housing characteristics, such as value and rent, will be obtained from the American Community Survey (ACS), which is separate from Census 2010.

A decennial census also brings a change in geography. For more information about the Census 2010 geography, see Census 2010 Geography Release.

Census glossary

Use this app to view the Census definition of attributes included in the Census and ACS databases.

View the Census glossary

Census tract

Census tracts are small statistical subdivisions of a county, with 1,200 to 8,000 residents typically. The boundaries are usually delineated by local committees and do not cross county or state lines. Tracts are identified by a six-digit code, with an implied decimal between the fourth and fifth digit.

Color-coded map

Also called a thematic map, it displays geographic areas according to specific values. For example, it could be a map showing census tracts in different colors according to median household income. Light green would represent lower income, medium green would represent a higher income level, and dark green would represent the highest level. A map of drive times is another example of this kind of map.

Congressional districts (CDs)

Congressional districts are the areas from which individuals are elected to the U.S. House of Representatives. Once the apportionment of congressional seats is made based on census population counts within a state, each state establishes CDs to elect representatives. A congressional district is uniquely identified using a two-digit state FIPS code and a two-digit CD FIPS code.

Consumer Expenditure (CEX) data

This comprehensive database, developed by Esri, is based on a combination of the latest Consumer Expenditure Surveys (CEX) from the Bureau of Labor Statistics and Esri's Tapestry Segmentation data. Data is reported by product or service and includes total expenditures, average spending per household, and a Spending Potential Index (SPI). See Consumer Spending Methodology (PDF).

Core Based Statistical Area (CBSA)

Core Based Statistical Areas, which include metropolitan and micropolitan statistical areas, are comprised of one or more counties and are defined by the U.S. Office of Management and Budget (OMB). A metropolitan statistical area is affiliated with at least one urbanized area of 50,000 or more inhabitants. A micropolitan statistical area is associated with at least one urban cluster of at least 10,000 people, but less than 50,000.


Counties are the primary legal divisions of a state, identified by a two-digit state FIPS code and a three-digit county FIPS code. See FIPS code.

County subdivisions (CSDs)

County subdivisions are the primary divisions of counties and include census county divisions (CCDs), minor civil divisions (MCDs), census subareas, and unorganized territories. CSDs can be uniquely identified using a two-digit state FIPS code, three-digit county FIPS code, and five-digit CSD FIPS code.

Data collection

A data collection is a preassembled list of attributes that are used to enrich the input features. Collection attributes can describe various types of information, such as demographic characteristics and geographic context, of the locations or areas submitted as input features.

Some data collections can be used in all supported countries. Other data collections may only be available in one or a collection of countries. Data collections may only be available in a subset of countries because of differences in the demographic data that is available for each country.


One or more structured sets of persistent data, managed and stored as a unit and generally associated with software to update and query the data. A simple database might be a single file with many records, each of which references the same set of fields. A GIS database includes data about the spatial locations and shapes of geographic features recorded as points, lines, areas, pixels, grid cells, or TINs, as well as their attributes.

Demographic data

The Esri Updated Demographic data includes current-year estimates and five-year projections for key demographic data. With the exception of the Tapestry Segmentation data, which is not available at the block group level of geography in the standard product, all data is available at census block group, census tract, county, state, U.S., CBSA, DMA, and ZIP Code levels of geography.


The statistical characteristics of a population-income, education, race, home ownership, and so on.

Designated Market Area (DMA)

Designated Market Areas are television markets defined by The Nielsen Company, revised on an annual basis. The majority of DMAs are comprised of one or more whole counties, although a few include parts of counties.

Diversity index

The diversity index summarizes racial and ethnic diversity. The index shows the likelihood that two persons, chosen at random from the same area, belong to different race or ethnic groups. The index ranges from 0 (no diversity) to 100 (complete diversity). For example, a diversity index of 59 means there is a 59 percent probability that two people randomly chosen would belong to different race or ethnic groups.


Households in which one or more persons in the household are related to the householder (formerly, the head of the household) by birth, marriage, or adoption. The census tabulates only one family per household.

FIPS code

Federal Information Processing Standards (FIPS) for numeric codes used to identify states and counties.

Hispanic origin

Defined by self-identification, Hispanic origin refers to ethnicity, not race. Persons of Hispanic origin may be of any race.

Home value

The estimate of value is presented for total owner-occupied units. For a discussion of home value projections, see the Demographic Updates Methodology (PDF).

Median home value

This estimate divides the distribution of home value into two equal parts. Linear interpolation is used if the median home value falls below $1,000,000. If the median falls in the upper home value interval of $1,000,000+, it is represented by $1,000,001.


A household is an occupied housing unit. Household type is identified by the presence of relatives and the number of persons living in the household. Family households, with or without children, include married couples and other families—a male or female householder with no spouse present. Non-family households may be a group of unrelated persons or a single person living alone.

Average household size

Average household size is calculated by dividing the number of persons in households by the number of households.

Household income

See Income.

Household income base

This is the sum of the household income distribution.

Housing Affordability Index

Esri's Housing Affordability Index (HAI) by Tapestry is defined as the financial ability of a typical household to purchase a typical home in each market segment. Esri's household income and home value estimates are the foundation of the model, complemented by regional property tax rates from the 2012 American Community Survey. There are three key assumptions of the model: (1) a 20 percent down payment and no mortgage insurance on the home loan; (2) the mortgage rate used is a national average published by the Federal Housing Finance Agency, and (3) debt service ratios are applied from the Federal Housing Administration. An HAI of 100 represents an area that, on average, has sufficient household income to qualify for a loan on a home valued at the median home price. An index greater than 100 suggests homes are easily afforded by the average area resident. Values less than 100 suggest that homes are less affordable in the market.


Income amounts are expressed in current dollars, including an adjustment for inflation or cost-of-living increases. For a discussion of income projections, see the Demographic Updates Methodology (PDF).

Median household income

This is the value that divides the distribution of household income into two equal parts. Pareto interpolation is used if the median falls in an income interval other than the first or last. For the lowest interval, < $10,000, linear interpolation is used. If the median falls in the upper income interval of $500,000+, it is represented by the value of $500,001.

Per capita income

This is the average income for all persons calculated from the aggregate income of persons 15 years and older.


An index is the ratio of a local percent (rate) to a national percent (rate) or other base. An index at the national level is 100, representing overall demand. A value of more than 100 represents higher demand, and a value of less than 100 represents lower demand than the country as a whole. Using the variable of dollars spent on airline fares as an example, if you calculated the index of this variable as 100, it would indicate that the area purchased airline tickets at the same rate as the national average. An index value of less than 100 indicates a value less than the national average and a value greater than 100 indicates purchases of airline fares at greater than the national average. An index of 200 for a given study area would indicate that households in the area purchase airline fares at twice the national average.

Leakage/Surplus Factor

The Leakage/Surplus Factor is included in the Retail MarketPlace database. It measures the balance between the volume of retail sales (supply) generated by retail businesses and the volume of retail potential (demand) produced by household spending on retail goods within the same industry. For more information about the Leakage/Surplus Factor, see Retail MarketPlace Leakage/Surplus Factor Data Note (PDF).


This is a value that divides a distribution into two equal parts. A median is a positional measure that is unaffected by extremely high or low values in a distribution that may affect an average. For more information about medians, see Understanding Medians (PDF).

Median age

See Age.

Median home value

See Home value.

Median household income

See Income.

Per capita income

See Income.

Places (cities and towns)

Places include incorporated places (usually cities, towns, villages, or boroughs), census designated places, and balance portions of consolidated cities. Places are uniquely identified using a two-digit state FIPS code and a five-digit place FIPS code.


This is the total number of residents in an area. Residence refers to the "usual place" where a person lives, which is not necessarily the legal residence. For example, college students are counted where they attend school.


Defined by self-identification, race detail from Census 2000 was expanded to include a multiracial component. For the first time, each individual could report up to six race categories, resulting in 63 possible race combinations. The six basic race categories are White, Black or African American, American Indian or Alaskan Native, Asian, Native Hawaiian or Other Pacific Islander, and "some other" race for persons who do not identify with one of the specified groups.


Segmentation explains customer diversity, simplifies marketing campaigns, describes lifestyle and lifestage, and incorporates a wide variety of data. See Tapestry Segmentation Methodology (PDF).

Shopping Center data

Directory of Major Malls tracks information on over 8,000 major shopping centers and malls across the United States. The file used in Business Analyst includes all shopping centers with a gross leasable area (GLA) of approximately 225,000+ square feet. Lifestyle/Specialty centers of any size are also included in this file, as this classification of centers has recently become a primary focus in shopping center development. In addition, the data in Business Analyst contains the data for up to four anchor stores.

Socioeconomic Index

The Esri Socioeconomic Index represents the relative social and economic status of the residents of each Tapestry segment. The value is a composite of select characteristics covering measures of financial well-being, educational attainment, and labor force characteristics such as employment status, occupation, and type of employment. The index is the ratio of the socioeconomic status of the Tapestry segment relative to the national average. Values above 100 indicate an above-average status.


States are identified by a two-digit FIPS code. The District of Columbia is included as a state-equivalent area in the Esri database. See FIPS code.

Tapestry Segmentation data

Esri's Tapestry Segmentation system provides an accurate, detailed description of America's neighborhoods. U.S. residential areas are divided into 67 segments based on demographic variables such as age, income, home value, occupation, household type, education, and other consumer behavior characteristics.

Thematic map

Also called a color-coded map, it displays study areas according to specific values. For example, it could be a map showing census tracts in different colors according to median household income. Light green would represent lower income, medium green would represent a higher income level, and dark green would represent the highest level. A map of drive times is another example of this kind of map.


A symbol or quantity that can represent any value or set of values, such as a text string or number. Variables may change depending on how they are used and applied. Variables are also known as fields, attributes, or columns.


The vintage is the year that the demographic data represents. For example, a vintage of 2016 means that the data represents the year 2016.

Wealth Index

Esri's Wealth Index is compiled from a number of indicators of affluence that include average household income and average net worth. The concept of wealth is defined by more than just above-average household income. Wealth also includes the value of material possessions and resources. Esri captures both income and the accumulation of substantial wealth, or the abundance of possessions and resources in its identification of the wealthiest areas in the country. The index represents the relative wealth of the Tapestry market segment to the national level. Values exceeding 100 represent above-average wealth.

ZIP Code

Created by the U.S. Postal Service to deliver the mail, ZIP Codes do not represent standard census geographic areas for data reporting. Because ZIP Code boundaries are not contiguous with census geographic areas or stable over time, data estimated for ZIP Codes is also subject to change.