NAEP Assessment Sample Design → NAEP 2009 Sample Design → Sample Design for the 2009 National Assessment → Hands-On Tasks (HOT) and Interactive Computer Tests (ICT) for the 2009 Science Assessment → Public School 2009 Science HOT and ICT Assessments → Stratification of Public Schools for the 2009 Science HOT and ICT Assessments

NAEP Technical DocumentationStratification of Public Schools for the 2009 Science HOT and ICT Assessments

Prior to stratification, the public school sampling frame was divided into grade-specific files, one each for fourth, eighth, and twelfth grade. For each grade-specific frame file, separate implicit stratification schemes were used to sort schools into certainty primary sampling units (PSUs) and noncertainty PSUs. In all cases, the implicit stratification was achieved via a "serpentine sort."

For certainty PSUs, the schools were hierarchically sorted by

• census region,
• urbanization classification (urban-centric locale), and
• median household income in the ZIP code area where the school is located.

Schools in noncertainty PSUs were hierarchically sorted by

• PSU stratum,
• urbanization classification (urban-centric locale), and
• median household income in the ZIP code area where the school is located.

 

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