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NAEP Weighting Procedures → 2002 Weighting Procedures and Variance Estimation → National Main Assessment Weights → Computation of Base Weights → Computation of Private School Base Weights

NAEP Technical DocumentationComputation of Private School Base Weights

			Trimming of School Base Weights

Each private school from the Private School Universe Survey (PSS) area probability sample (see Sampling Frame for the 2002 National Main Assessment) should have an extra factor included in its probability of selection that represents the probability of its selection into the PSS area probability sample. In some cases this area probability of selection was very small. For this reason the private school's weight was trimmed if it was more than three times larger than what it would have been without the area probability component, so that the private school and its weight would not contribute excessively to the mean square error.

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