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NAEP Weighting Procedures → Weighting Procedures and Variance Estimation for the 2000 National Main Assessment → Reporting Weights Main → Initial Student Weight for the 2000 National Main Assessment → School Base Weight for the 2000 National Main Assessment

NAEP Technical DocumentationSchool Base Weight for the 2000 National Main Assessment

The school base weight reflects the probability of a school being selected for assessment for a given subject. It is calculated separately by grade and subject and is the product of five factors:

The subject-specific school base weight (SCHBWT) is expressed as the product

SCHBWT = PSUWGT_M x RSCHWT x SCH_WT x ASBJWT x STYWT

where

• PSUWGT M = PSU weight, the reciprocal of the probability that the primary sampling unit (PSU) was selected;

• RSCHWT = PSS weight, the reciprocal of the probability that a private school was included on the Private School Survey file (assigned a value of 1.0 for public schools);

• SCH_WT = school weight, the reciprocal of the conditional probability, given the PSU, that the school was selected;

• ASBJWT = subject assignment weight, the reciprocal of the conditional probability, given the sample of schools in a PSU, that the school was allocated the specified subject; and

• STYWT = sample type weight, the reciprocal of the probability that the school was assigned the specified sample type.

A school that replaces a refusing school (i.e., a substitute school) is assigned the weight of the refusing school. Therefore the substitute school is treated as if it were the original school that it replaced for purposes of obtaining school base weights. The subject assignment weight (ASBJWT) for a substitute school is adjusted if it is not large enough to assess all sessions or subjects assigned to the original school.

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