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NAEP Assessment Sample Design → NAEP 2007 Sample Design → Sample Design for the 2007 State Assessment → Stratification of Schools for the 2007 State Assessment → Stratification Variables for the 2007 State Assessment → Stratification by Urbanization Classification for the 2007 State Assessment

NAEP Technical DocumentationStratification by Urbanization Classification for the 2007 State Assessment

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

• Atlanta City School District, Georgia;
• Austin Independent School District, Texas;
• Boston School District, Massachusetts;
• Charlotte-Mecklenburg Schools, North Carolina;
• City of Chicago School District 299, Illinois;
• Cleveland Municipal School District, Ohio;
• Houston Independent School District, Texas;
• Los Angeles Unified School District, California;
• New York City Public Schools, New York; and
• San Diego Unified School District, California

Schools in these districts were divided 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. For states without TUDA districts, and for portions of TUDA states outside of the TUDA districts, the urbanization classification contains the following categories:

1. Large City: A principal city of a Metropolitan Core Based Statistical Area (CBSA), with the city having a population greater than or equal to 250,000.

2. Mid-size City: A principal city of a Metropolitan CBSA, with the city having a population less than 250,000.

3. Urban Fringe of a Large City: Any incorporated place, Census-designated place, or non-place territory within a Metropolitan CBSA of a Large City and defined as urban by the Census Bureau.

4. Urban Fringe of a Mid-size City: Any incorporated place, Census-designated place, or non-place territory within a CBSA of a Mid-size City and defined as urban by the Census Bureau.

5. Large Town: An incorporated place or Census-designated place with a population greater than or equal to 25,000 and located outside a Metropolitan CBSA or inside a Micropolitan CBSA.

6. Small Town: An incorporated place or Census-designated place with population less than 25,000 and greater than or equal to 2,500 and located outside a Metropolitan CBSA or inside a Micropolitan CBSA.

7. Rural, outside CBSA: Any incorporated place, Census-designated place, or non-place territory not within a Metropolitan CBSA or within a Micropolitan CBSA and defined as rural by the Census Bureau.

8. Rural, inside CBSA: Any incorporated place, Census-designated place, or non-place territory within a Metropolitan CBSA and defined as rural by the Census Bureau.

9. Outside of the United States: Department of Defense (DoD) International school or Puerto Rico.

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, type of location categories 1 and 2 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 type of location (category 9) is always kept as a separate stratum.

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