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NAEP Technical DocumentationStratification by Urbanization Classification for the 2009 State Assessment

The urbanization classification was based on the definition of Trial Urban District Assessment (TUDA) districts for states that have TUDA districts and on the NCES urban-centric locale variable. The TUDA districts are as follows:

Schools in these districts were divided into their own jurisdiction, separate from the schools in the remaining portions of each of these states. In California, for example, separate jurisdictions were created for the TUDA districts in Fresno, Los Angeles and San Diego as well as a jurisdiction for the balance of the state. Within each jurisdiction, the NCES urban-centric locale contains the following categories:

11. Large City: Territory inside an urbanized area and inside a principal city with population of 250,000 or 
     more.

12. Mid-size City: Territory inside an urbanized area and inside a principal city with population less than 
     250,000 and greater than or equal to 100,000.

13. Small City: Territory inside an urbanized area and inside a principal city with population less than
     100,000.

21. Large Suburb: Territory outside a principal city and inside an urbanized area with population of 250,000 or
     more.

22. Mid-size Suburb: Territory outside a principal city and inside an urbanized area with population less than
     250,000 and greater than or equal to 100,000.

23. Small Suburb: Territory outside a principal city and inside an urbanized area with population less than
     100,000.

31. Fringe Town: Territory inside an urban cluster that is less than or equal to 10 miles from an urbanized
     area.

32. Distant Town: Territory inside an urban cluster that is more than 10 miles and less than or equal to 35
     miles from an urbanized area.

33. Remote Town: Territory inside an urban cluster that is more than 35 miles of an urbanized area.

41. Fringe Rural: Census-defined rural territory that is less than or equal to 5 miles from an urbanized area,
     as well as rural territory that is less than or equal to 2.5 miles from an urban cluster.

42. Distant Rural: Census-defined rural territory that is more than 5 miles but less than or equal to 25 miles
     from an urbanized area, as well as rural territory that is more than 2.5 miles but less than or equal to 10
     miles from an urban cluster.

43. Remote Rural: Census-defined rural territory that is more than 25 miles from an urbanized area and is
     also more than 10 miles from an urban cluster.

99. Outside of the United States: Department of Defense Education Activity (DoDEA) overseas schools.

For the definitions of the geographic terms used in these descriptions, please refer to the Census Bureau’s website (for example, www.census.gov/geo/www/ua/ua_2k.html; www.census.gov/population/www/metroareas/aboutmetro.html)

This portion of the urbanization classification was created by starting with the original NCES urban centric locale categories. The criterion for adequacy of a stratification cell is that the cell has at least a minimum percentage of the student enrollment for the jurisdiction. The criterions were 12 percent in large TUDA districts (Los Angeles, New York City, Chicago, Miami, and Houston), 18 percent in all other TUDA districts, and 9 percent in all other jurisdictions.

The urbanization variable is equal to the original NCES urban-centric locale if no collapsing is necessary to cover an inadequate original cell (less than the above criterion). If collapsing is necessary, the collapsing scheme will first collapse within the four major strata (City, Suburbs, Town, Rural), using the order as given in the above list. For example, urbanicity categories 11, 12, and 13 within City are collapsed in order of the list (11 with 12, 12 with 13) if cells 11 or 13 are deficient. If the middle cell (e.g., 12) is the deficient one, then it is collapsed with the smaller of the two end cells. If a pair is still deficient, it is collapsed with the remaining unit within the major stratum. That is, a single category would be created by combining Large City, Mid-size City and Small City. If these collapsed cells are still inadequate, they are further collapsed with all three types of Suburb cells to form a single cell made up of large, mid-size and small cities and large, mid-size and small suburbs. 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 suburb fringe areas are always kept separate from towns and rural areas, even if the enrollment criterion is violated. Finally, the outside of the United States category (Category 99) is always kept as a separate stratum.

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