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NAEP Assessment Weighting Procedures → Weighting Procedures and Variance Estimation for the 2004 Assessment → Computation of Full-Sample Weights for the 2004 Assessment → Computation of Base Weights for the 2004 Assessment → School Base Weights for the 2004 Assessment

NAEP Technical DocumentationSchool Base Weights for the 2004 Assessment

The school base weight for a sampled school is equal to the inverse of its probability of selection. The computation of the school base weight differs by whether the school was an originally selected school or a substitute school.

The school base weight for an originally selected school is equal to the inverse of its overall probability of selection. The school overall probability of selection is equal to the product of two quantities:

• the probability of selection of the primary sampling unit, (PSU), and
• the probability of selection of the school within the selected PSU.

A school that takes the place of a refusing original school is known as a "substitute school". A substitute school is treated as if it were the original school that it replaced, and so is assigned the school base weight of the original school.

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