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Computation of Base Weights for the 2004 Assessment



School Base Weights

Student Base Weights

Every sampled school and student received a base weight equal to the reciprocal of its probability of selection. Computation of a school base weight varies by whether the school was an originally selected school (i.e., not a substitute school), or a substitute school.

Computation of a student base weight reflects

  • the student's overall probability of selection accounting for school and student sampling,
  • the school and student assessment type assignment (operational or bridge assessment), and
  • the student's assignment to the mathematics or reading assessment. 

Last updated 03 November 2009 (GF)

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National Center for Education Statistics -
U.S. Department of Education