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NAEP Sample Design → NAEP 2003 Sample Design → 2003 State Assessment Sample Design → Stratification of Schools in the 2003 State Assessment → Stratification Variables → Stratification by Urbanization Classification

NAEP Technical DocumentationStratification by Urbanization Classification

The urbanization classification was based on the definition of Trial Urban District Assessment (TUDA) districts for states which have TUDA districts, and on the NCES type of location variable. The TUDA districts are as follows:

• Los Angeles, California;
• San Diego, California;
• Atlanta, Georgia;
• Chicago, Illinois;
• Boston, Massachusetts;
• Albuquerque, New Mexico;
• New York City, New York;
• Charlotte, North Carolina;
• Cleveland, Ohio; and
• Houston, Texas.

Schools in these districts were classified into their own urbanization strata, separate from the strata defined below for schools in the remaining portions of each of these states. In California, for example, separate strata were created for the TUDA districts in Los Angeles and San Diego as well as strata for the rest of the state based on type of location. Albuquerque, although originally sampled as a TUDA, declined participation in the TUDA portion of the study, but did contribute to the estimates for the state of New Mexico. For states without TUDA districts, and for portions of TUDA states outside of the TUDA districts, the urbanization contains the following categories:

• Large Central City : A central city of a metropolitan statistical area (MSA) with a population greater than or equal to 250,000;

• Mid-Size Central City : A central city of an MSA with a population less than 250,000;

• Urban Fringe of Large City : A place within an MSA of a large central city and defined as urban by the U.S. Bureau of Census, but not within the boundaries of the central city;

• Urban Fringe of Mid-Size City : A place within an MSA of a mid-size central city and defined as urban by the U.S. Bureau of Census, but not within the boundaries of the central city;

• Large Town : A place not within an MSA, but with a population greater than or equal to 25,000 and defined as urban by the U.S. Bureau of Census;

• Small Town : A place not within an MSA, with a population less than 25,000, but greater than 2,499 and defined as urban by U.S. Bureau of Census;

• Rural : A place with a population of less than 2,500 and defined as rural by the U.S. Bureau of Census;

• MSA Rural : A place defined as rural within an MSA; and

• Missing : DoDDS or type of location missing (whole jurisdiction).

This portion of the urbanization classification was created by starting with the original type of location categories. The criterion for adequacy of a stratification cell is that the cell has at least 10 percent of the student enrollment for the jurisdiction. The urbanization variable is equal to the original type of location if no collapsing is necessary to cover an inadequate original cell (less than 10 percent enrollment). For example, the first two type-of-location categories are collapsed if either cell has less than 10 percent enrollment. That is, a single category would be created by combining Large Central City with Mid-size Central City. If these collapsed cells are still inadequate, they are further collapsed with the two types of Urban Fringe cells to form a single cell made up of large and mid-size cities and the urban fringes of large and mid-size cities. The urbanization variable is equal to the cell value of the final level of collapsing. Prior experience with this type of stratification has shown that the greatest efficiency of stratification results when cities and urban fringe areas are always kept separate from towns and rural areas, even if the 10 percent condition is violated. Finally, the last type-of-location category (Category: Missing) is always kept as a separate stratum.

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