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NAEP Sample Design → NAEP 2002 Sample Design → 2002 National Main Assessment Sample Design → Stratification of Schools → Stratification for Twelfth-Grade Public Schools

NAEP Technical DocumentationStratification for Twelfth-Grade Public Schools

The stratification of twelfth-grade public schools was a hierarchical stratification with the following dimensions:

• Census division,¹

• Type of location,²

• Minority status (whether the school had 15% or more Blacks and Hispanics, or not),

• School type (regular public, state-run public, Bureau of Indian Affairs (BIA) schools, or Department of Defense (DoD) school), and

• Estimated grade enrollment.

A check was made of the strata defined by Census division and types of location, to ensure that an expected sample size of at least four schools was represented by the stratum. If not, the type-of-location strata were collapsed following the collapsing rules given in the state assessment’s urban classification guidelines. Only a few strata needed to be collapsed.

The implicit stratification in this five-fold hierarchical stratification is achieved via a serpentine sort, as utilized for the 2002 NAEP state assessment’s stratification variables (see 2002 State NAEP stratification).

¹ New England, Middle Atlantic, East North Central, West North Central, South Atlantic, East South Central, West South Central, Mountain, and Pacific.
² "Type of location" is defined as an interval variable is 1=center of large city, 2=center of mid-size city, 3=urban fringe of large city, 4=urban fringe of mid-size city, 5=large town, 6=small town, 7=rural area, 8=rural area in Metropolitan Statistical Area (MSA). A mean value of 6.0 for example can mean all in small town, or half in urban fringe of mid-size city and half in rural area of MSA stratum.

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