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Note 1: Commonly Used Variables (2008)

Certain common variables, such as parents’ education, race/ethnicity, community type, poverty, and geographic region are used by different surveys cited in The Condition of Education 2008. The definitions for these variables can vary across surveys and sometimes vary between different time periods of a single survey. This supplemental note describes how several common variables, used in various indicators in this website, are defined in each of the surveys. In addition, this note describes certain terms used in several indicators.


Parents’ level of education is generally measured by either the mother’s highest level of education attained or the highest level of education attained by either parent. Indicators


Classifications indicating racial/ethnic heritage are based primarily on the respondent’s self-identification, as is the case with data collected by the U.S. Census Bureau, or in rare instances, on observer identification. These categories are in accordance with the Office of Management and Budget’s standard classification scheme.

Ethnicity is based on the following categorization:

Race is based on the following categorization:

Race categories presented in The Condition of Education 2008 exclude persons of Hispanic ethnicity; thus, the race/ethnicity categories are mutually exclusive. Not all categories are shown in all indicators. In some cases, categories are omitted because there are insufficient data in some of the smaller categories or because survey sampling plans did not distinguish between groups (between Asians and Pacific Islanders, for example). In other cases, omissions occur because only comparable data categories are shown. For example, the category “More than one race,” which was introduced in the 2000 Census and became a regular category for data collection in the Current Population Survey (CPS) in 2003, is sometimes excluded from indicators that present a historical series of data with constant categories, and it is sometimes included within the category “Other.”

The introduction of the category “More than one race” follows a change in the Office of Management and Budget’s standard classification scheme for race/ethnicity. This change has required changes to the questions asked by the CPS, and it will require further changes to the questions asked of future federal survey participants. As a result of the new classification scheme, distributions by race/ethnicity for 2003 CPS data and for later years may differ somewhat from those in earlier years. In the Census population estimates for July 1, 2007, about 1.6 percent of the national population were classified as “More than one race.” (For further details, see

In The Condition of Education 2008, the above definitions of race/ethnicity apply to indicators


There are various classification systems that federal departments and agencies use to define community types. Indicators in The Condition of Education rely on one or a combination of the following three classification systems: the Office of Management and Budget’s system of metropolitan areas, which is used by the Census Bureau; the Census Bureau’s system of urbanized/urban/rural areas; and the National Center for Education Statistics (NCES) system of locale codes. All three of these classification systems were revised in 2000 and were fully in effect by 2003. In 2006, a new urban-centric classification system for NCES locale codes was released.

Metropolitan Areas

The Census Bureau’s Current Population Survey (CPS) classifies community type based on the concept of a metropolitan area, which has changed in its application over time. Between 1990 and 2000, the Census and the CPS used the term “metropolitan area” (MA) to refer collectively to Metropolitan Statistical Areas (MSAs), Primary Metropolitan Statistical Areas (PMSAs), and Consolidated Metropolitan Statistical Areas (CMSAs) (defined below). In 2000, the Census adopted the term “Core Based Statistical Area” (CBSA), which refers collectively to metropolitan statistical areas and (the newly introduced concept of) micropolitan statistical areas.

Metropolitan Areas—1990 Standards

The Office of Management and Budget (OMB) defines and designates metropolitan areas, following standards established by the interagency Federal Executive Committee on Metropolitan Areas, with the aim of producing definitions that are as consistent as possible for all MAs nationwide. Under its 1990 standards, the OMB defined an MA as “a large population nucleus together with adjacent communities that have a high degree of economic and social integration with that core.” The Census Bureau used this definition for an MA from 1990 to 2000. (See for more details.)

In order to be designated as an MA under the 1990 standards, an area had to meet one or both of the following criteria: (1) include a city with a population of at least 50,000 or (2) include a Census Bureau-defined urbanized area of at least 50,000 and have a total MA population of at least 100,000 (75,000 in New England). Under the 1990 standards, the “central county” (or counties) contained either the central city (defined below) or at least 50 percent of the population of the central city, or had at least 50 percent of its population in an urbanized area. Additional ‘‘outlying counties’’ were included in the MA if they met specified requirements of commuting to the central counties and selected requirements of metropolitan character (such as population density and percent urban). In New England, MAs were defined in terms of cities and towns, following rules analogous to those used with counties elsewhere.

The individual counties (or other geographic entities) comprising each MA were either designated as a Metropolitan Statistical Area (MSA) or, if the MA was large enough (1 million in population or more), as a Consolidated Metropolitan Statistical Area (CMSA) composed of two or more Primary Metropolitan Statistical Areas (PMSAs). For example, the PMSA “Milwaukee-Waukesha, WI” combined with the PMSA “Racine, WI” to form the CMSA of “Milwaukee-Racine, WI.” CMSAs could span states, as was the case with the CMSA “Philadelphia-Wilmington-Atlantic City, PANJ-DE-MD.” (In June 1999, there were 258 MSAs and 18 CMSAs in the United States, which included a total of 73 PMSAs.)

All territory, population, and housing units inside of MAs were characterized as metropolitan. Any territory, population, or housing units located outside of an MA were defined as nonmetropolitan. The largest city in each MA was designated a central city, and additional cities could qualify as such if specified requirements were met concerning population size and commuting patterns. (In June 1999, there were 542 central cities in the United States plus 12 in Puerto Rico.)

Together these classifications were used to define a location’s MA Status as

  1. Central city,

  2. Balance of an MA (meaning any territory that is metropolitan but not in a central city), or

  3. Nonmetropolitan.

Metropolitan and Micropolitan Statistical Areas—2000 Standards

In 2000, the OMB defined metropolitan and micropolitan statistical areas as “a core area containing a substantial population nucleus, together with adjacent communities having a high degree of economic and social integration with that core.” Together metropolitan and micropolitan statistical areas are considered to constitute the “Core Based Statistical Area” (CBSA). Currently defined metropolitan and micropolitan statistical areas are based on the application of OMB’s 2000 standards to 2000 decennial census data. (Current metropolitan and micropolitan statistical area definitions were announced by OMB effective June 6, 2003.)

In order to be designated as a CBSA under the 2000 standards, an area must contain at least one “urban” area (that is, an urbanized area or urban cluster—see definitions of urbanized area and urban cluster below) with a population of 10,000 or more. Each metropolitan statistical area—now referred to as a “metro area” to distinguish it from the metropolitan statistical areas referred to as “MSAs” under the 1990 standards—must have at least one urbanized area of 50,000 or more inhabitants. Each micropolitan statistical area must have at least one urban cluster of at least 10,000 but less than 50,000 population. Under the standards, the county (or counties) in which at least 50 percent of the population resides within urban areas of 10,000 or more population, or that contains at least 5,000 people residing within a single urban area of 10,000 or more population, is identified as a “central county” (counties). Additional “outlying counties” are included in the CBSA if they meet specified requirements of commuting to or from the central counties. Counties or equivalent entities form the geographic “building blocks” for metropolitan and micropolitan statistical areas throughout the United States and Puerto Rico. (As of June 6, 2000, there were 362 metropolitan statistical areas and 560 micropolitan statistical areas in the United States. In addition, there were eight metro areas and five micropolitan statistical areas in Puerto Rico.) (See for more details.)

Together, these classifications are used to define a location’s CBSA status (or, if no micropolitan statistical areas are included, metro area status) as

  1. Principal city of a CBSA (or metro area).

  2. Located in a CBSA (or metro area), but not in the principal city.

  3. Not located in a CBSA (or metro area).

As with the previous MA status classifications under the 1990 standards, the CBSA status classifications under the 2000 standards do not equate to an urban-rural classification; all counties included in metropolitan and micropolitan statistical areas (and many other counties) contain both.

In The Condition of Education 2008, no indicators use these labels and definitions. However, indicators

Urbanized, Urban, and Rural Areas

The Census Bureau divides the entire geographic area of the United States, Puerto Rico, and the Island Areas according to a concept of urban and rural areas. As with metropolitan statistical areas, the Census Bureau revised the urban/rural concept and criteria for the 2000 Census. The criteria in place between 1990 and 2000, however, were used to create the NCES codes (described below). Thus, this supplemental note explains the 1990–2000 criteria in detail for readers to understand fully the definitions.

From the adoption of the urban/rural concept for the 1950 Census until the 2000 Census, an urbanized area consisted of one or more “central places” and the adjacent densely settled surrounding “urban fringe” that together had a minimum population of 50,000 people. A “place” was either an incorporated governmental unit, such as a city, village, borough, or town, or a Census Designated Place (CDP), which was an unincorporated population cluster for which the Census Bureau delineates boundaries in cooperation with state and local agencies. All of the territory within the urbanized area that was outside the central place or places comprised the “urban fringe.” Territory included in the urban fringe generally had a population density of at least 1,000 people per square mile but could include lower density territory that contained nonresidential urban land uses (e.g., areas zoned for commercial or industrial use or reserved for recreational purposes) or served to link outlying densely settled territory with the main body of the urbanized area. The Census Bureau defined as urban any incorporated places (cities, towns, villages, etc.) or CDPs outside urbanized areas that contained a population of 2,500 or more.

The Census Bureau also expanded the definition of places to include extended cities. Extended cities were incorporated places whose boundaries encompassed substantial amounts of low-density territory (less than 100 people per square mile), relative to the overall land area of the place. The Census Bureau then identified both urban and rural territory in such places, thus providing exceptions to the general rule that places were classified as entirely urban or entirely rural. There were 182 extended cities in 1990. The decision to ignore place boundaries when defining urban areas for the 2000 Census (see below) made the extended city concept obsolete; under the 2000 criteria, any place potentially can be divided into urban and rural components. No survey employed in this volume of The Condition of Education includes extended cities in its community type definition.

The Census Bureau then classified all territory, population, and housing units not classified as urbanized or urban as rural. (For further details, see

Beginning with the 2000 Census, the Census Bureau has employed new definitions of urban areas based on the concepts of an urbanized area and an urban cluster, the former being similar to the urbanized area under the 1990 definitions and the latter replacing the concept of urban fringe and urban areas. Urbanized areas and urban clusters consist of densely settled census block groups and census blocks that meet specified minimum population density requirements. Urbanized areas continue to have minimum populations of 50,000; urban clusters have populations of at least 2,500 and less than 50,000. Place boundaries are no longer taken into consideration when defining these two types of urban areas. (Under the previous classification system, place boundaries were used to determine the urban/rural classifications of territory: all incorporated places that had at least 2,500 people were classified as urban if they were outside an urbanized area.) Thus, the Census Bureau’s current urban area classification provides a seamless, nationally consistent method of defining urban areas that is not affected by varying state laws governing incorporation and annexation. For further details on the revised definitions, see (For differences between the 1990 Census and 2000 Census Urbanized Area Criteria, see

Locale Code

In the NCES Common Core of Data (CCD), the community type of schools is classified according to an urban-centric “Locale Code” system. Locale codes are assigned to each school according to the school’s physical location (longitude and latitude). There are four major categories within the urban-centric locale code classification system: (1) city, (2) suburban, (3) town, and (4) rural. Each major category is divided into three subcategories. Cities and suburban areas are subdivided into the categories of small, midsize, and large; towns and rural areas are subdivided by their proximity to an urbanized area into the categories of fringe, distant, and remote (see exhibit B). These 12 categories are based on three key concepts that the Census Bureau uses to define an area’s urbanicity: principal city, urbanized area, and urban cluster. A principal city is a city that contains the primary population and economic center of a metropolitan statistical area, which, in turn, is defined as one or more contiguous counties that have a “core” area with a large population nucleus and adjacent communities that are highly integrated economically or socially with the core. Urbanized areas and urban clusters are densely settled “cores” of Census-defined blocks with adjacent densely settled surrounding areas. Core areas with populations of 50,000 or more are designated as urbanized areas; those with populations between 25,000 and 50,000 are designated as urban clusters. For more information on urbanized areas and urban clusters, see Rural areas are designated by Census as those areas that do not lie inside an urbanized area or urban cluster.

NCES has classified all schools into one of these 12 categories based on schools’ actual addresses and their corresponding coordinates of latitude and longitude. Not only does this mean that the location of any school can be identified precisely, but also that distance measures can be used to identify town and rural subtypes. Unlike the previous classification system that differentiated towns on the basis of population size, the new system differentiates towns and rural areas on the basis of their proximity to larger urban centers.

School districts’ locale codes are assigned through the use of these urban-centric locale codes, according to classification rules, such as the following: if 50 percent or more of students in the district attend schools that are located in a single locale code, that code is assigned to the district. If no single locale code accounts for 50 percent of the students, then the major category (city, suburban, town, or rural) with the greatest percentage of students determines the locale. Districts with no schools or students are given a locale code of “N.” (For more information on the urban-centric locale code system, see

Besides being used for the CCD, the expanded 12-level locale codes are used to categorize community type in other NCES surveys. Typically, however, the locale codes are collapsed into the four major categories of city, suburban, town, and rural.

In The Condition of Education 2008, urban-centric locale codes are used in indicators


Data on household income and the number of people living in the household are combined with estimates of the poverty threshold published by the Census Bureau to determine the poverty status of children (or adults). The thresholds used to determine poverty status for an individual differ for each survey year. The weighted average poverty thresholds for various household sizes for 1990, 1995, and 2000 through 2007 are shown in the table on the next page. (For thresholds for other years, see

In indicators

Eligibility for the National School Lunch Program also serves as a measure of poverty status. The National School Lunch Program is a federally assisted meal program operated in public and private nonprofit schools and residential child care centers. Unlike the poverty thresholds discussed above, which rely on dollar amounts determined by the Census Bureau, eligibility for the National School Lunch Program relies on the federal income poverty guidelines of the Department of Health and Human Services. To be eligible for free lunch, a student must be from a household with an income at or below 130 percent of the federal poverty guideline; to be eligible for reduced-price lunch, a student must be from a household with an income at or below 185 percent of the federal poverty guideline. Title I basic program funding relies on free lunch eligibility numbers as one (of four) possible poverty measures for levels of Title I federal funding. In The Condition of Education 2008, eligibility for the National School Lunch Program applies to indicators


The goal of the Census Bureau’s Small Area Income and Poverty Estimates (SAIPE) program is to make intercensal estimates of median income and numbers in poverty for states, counties, and school districts.

Geographic Region

The regional classification systems below represent the four geographical regions of the United States as defined by the Census Bureau of the U.S. Department of Commerce. In The Condition of Education 2008, indicators

Exhibit A. Metropolitan Areas - 1990 and 2000 Standards

Metropolitan Areas - 1990 and 2000 Standards

Exhibit B. NCES urban-centric locale categories

NCES urban-centric locale categories

SOURCE: Office of Management and Budget (2000). Standards for Defining Metropolitan and Micropolitan Statistical Areas; Notice. Federal Register (65) No. 249.

Weighted average poverty thresholds, by household size: Selected years, 1990-2007

Weighted average poverty thresholds

SOURCE: U.S. Census Bureau, Current Population Survey (CPS). Retrieved April 9, 2008, from

U.S. Census Bureau, Regional Classification

U.S. Census Bureau, Regional Classification