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NAEP Technical DocumentationAchievement Score and Median Income

The achievement data variable is derived from the results of the state assessment programs and were obtained from each jurisdiction. The contents of the achievement data files varied by jurisdiction, and included achievement measures for a variety of subjects and 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 were judged as sufficiently complete. Achievement data were more recent, and thus were thought to be more correlated with achievement than median household income, and thus a more effective stratification variable. The achievement measures were identified according to the following criteria:

• Use achievement measures from state assessments conducted in reading, writing, or other language skills. 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 2000 assessments (the latest available) were preferred, with 1999 as a second choice.

• Use achievement measures that match to at least 70 percent of the schools on our sampling frames.

• Use achievement measures that differentiate among the schools well. For example, district-level measures or pass/fail indicators were judged not to be good differentiators. In addition, achievement measures where a majority of schools had levels higher than 90 percent were not judged to be good differentiators.

Achievement data files were received from 41 participating jurisdictions (of 56 total participating in State NAEP). Only participating jurisdictions for which we did not select all schools with certainty (so that stratification was necessary) are included in the stratification. For grade 4, achievement data was used for stratification in 39 jurisdictions (with 9 jurisdictions using median income), and for grade 8, achievement data was used in 31 jurisdictions (with 15 jurisdictions using median income). The data on median household income reflected the ZIP Code area in which the school is located. The data were derived from the 1990 Census and compiled from Donnelly Marketing Information Services.

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