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NAEP Weighting Procedures → 2002 Weighting Procedures and Variance Estimation → State Assessment Weights → Computation of Base Weights → Computation of School Base Weights for New Schools

NAEP Technical DocumentationSchool Base Weights for New Schools

New schools were selected from a new school frame, which, in turn, was developed from a canvassing of schools from selected school districts. The overall probability of selection for new schools  contains a factor for the probability of selection of the school district, and a factor for selection of the new school within the sampled school district. In some cases for small districts (with a low probability of selection of the school district),  was very large. To avoid efficiency losses, in these cases the weighting factor for new schools was a trimmed version of , attaching to the school base weights a trimming factor TRIM_s, computed as follows:

E_s^-1 is the weight the school would have received if its grade enrollment measure of size E_s determined its probability of selection, with no district sampling. If the final school weight  is more than three times larger than E_s^-1, the school weight is trimmed back to effectively equal 3 E_s^-1. If the final weight  is less than three times larger than E_s^-1, then the school weight is left as .

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