NAEP Technical DocumentationComputation of Full-Sample Weights for the 2007 Assessment

Computation of Base Weights

School and Student Nonresponse Adjustments

School and Student Weight Trimming Adjustments

The full-sample or final student weight is the sampling weight used to derive NAEP student estimates of population and subpopulation characteristics for a specified grade (4, 8, or 12) and operational subject (mathematics, reading, or writing). The full-sample student weight reflects the number of students that the sampled student represents in the population for purposes of estimation. The summation of the final student weights over a particular student group provides an estimate of the total number of students in that group within the population.

The full-sample weight, which is used to produce survey estimates, is distinct from a replicate weight that is used to estimate variances of survey estimates. The full-sample weight is assigned to participating students and reflects the student base weight after the application of the various weighting adjustments for school and student nonresponse, and school and student trimming. The full-sample weight for student k from school s in stratum j (FSTUWGT_jsk) can be expressed as follows:

where

STU_BWT_jsk is the student base weight;
SCH_NRAF_js is the school-level nonresponse adjustment factor;
STU_NRAF_jsk is the student-level nonresponse adjustment factor;
SCH_TRIM_js is the school-level weight trimming adjustment factor; and
STU_TRIM_jsk is the student-level weight trimming adjustment factor.

School sampling strata for a given assessment varies by school type and grade. See strata for the grades 4 and 8 public school samples; strata for the grade 12 public school sample; and strata for the private school sample at all 3 grades.

Last updated 07 April 2010 (GF)

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