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NAEP Technical DocumentationStratification by Race/Ethnicity Classification for the 2009 State Assessment

Race/ethnicity classification was based on the second and third largest race/ethnicity percentages (among Black, Hispanic, Asian, American Indian, and non-Hispanic White students) within each urbanization classification within a jurisdiction. Within these cells, the second largest group is considered the largest race/ethnicity group and the third largest group is considered the second largest race/ethnicity group. Three different race/ethnicity classification schemes were used, as follows:

Case 1: Urbanization classifications with less than 7 percent of students in the largest race/ethnicity group were not stratified by race/ethnicity enrollment (race/ethnicity stratification value was set to 0). There were no race/ethnicity strata within these domain-urbanicity cells (i.e., only one stratum was used for the domain-urbanicity cell).

Case 2: Urbanization classifications with greater than or equal to 7 percent of students in the largest group but with no more than one race/ethnicity with 15 percent or more of the population were stratified by ordering the sum of the percentage of race/ethnicity enrollment for the largest and next largest groups within the urbanization classification and dividing the schools into three groups with approximately equal numbers of students per race/ethnicity classification.

Case 3: In urbanization classifications with greater than 15 percent of students in both the largest and next largest groups, race/ethnicity classifications were formed with the objective of providing equal strata with emphasis on the two largest groups. The stratification was performed as follows: The largest group provided the primary stratification variable; the second largest group provided the secondary stratification variable. Within urbanization classification, the schools were first sorted based on the primary stratification variable. Then they were divided into two strata of schools containing approximately equal numbers of students based on estimated grade enrollment. Within each of these two strata, the schools were sorted by the secondary stratification variable and subdivided into two substrata of schools containing approximately equal numbers of students. As a result, within urbanization classification there were four race/ethnicity classifications (e.g., low primary variable/low secondary variable, low primary variable/high secondary variable, high primary variable/low secondary variable, and high primary variable/high secondary variable).

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