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NAEP Weighting Procedures → Weighting Procedures for the 2005 Assessment → Computation of Full-Sample Weights for the 2005 Assessment → Computation of Base Weights for the 2005 Assessment → School Base Weights for the 2005 Assessment

NAEP Technical DocumentationSchool Base Weights for the 2005 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 original, new, or a substitute school.

The school base weight for an original school is equal to the inverse of its probability of selection from the NAEP public or private school frame.

The school base weight for a new school is equal to the inverse of its overall probability of selection, which is the product of two components:

• the probability of selection of the school's district into the new-school district sample, and  
• the probability of selection of the school into the new school sample.

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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