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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 Achievement Data and Median Income

NAEP Technical DocumentationStratification by Achievement Data and Median Income

The achievement data are derived from the results of state assessment programs which were obtained from each jurisdiction. The contents of the achievement data files varied by jurisdiction and included achievement measures for a variety of subjects, grades, and multiple assessment programs. The achievement data files were processed in order to select one achievement measure that could be used in stratification for each jurisdiction and grade. The achievement data were used for implicit stratification for jurisdictions and grades for which they were available and sufficiently complete. Since the achievement data were more recent than the median household income data, they were judged to be a more effective stratification variable. The achievement measures were identified according to the following criteria:

• Use achievement measures from state assessments conducted in mathematics, reading, and language arts. For grade 4, use data from fourth-grade assessments if available; otherwise, use data from third-grade assessments. For grade 8, use data from eighth-grade assessments if available; otherwise use data from seventh-grade assessments. For both grades, data from 2001 assessments (the latest available) were preferred, or 2000 or 1999 as secondary choices.
  
  
• Use achievement measures that match to at least 70 percent of the schools on the sampling frames.
  
  
• Use achievement measures that distinguish schools among themselves effectively. For example, district-level measures, measures with high missing rates or pass/fail indicators were judged not to be good differentiators. In addition, achievement measures where most schools had levels higher than 90 percent were judged not to be good differentiators.

Achievement data were received from 45 participating jurisdictions. For grade 4, achievement data were used for stratification in 42 jurisdictions, and for grade 8, in 34 jurisdictions.

Where achievement data were not used, median household income was used. The data on median household income related to the ZIP Code area in which the school is located. The data were derived from the 1990 Census.

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