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NAEP Assessment Weighting Procedures → Weighting Procedures for the 2007 Assessment → Computation of Replicate Weights for the 2007 Assessment → Computing Student-Level Replicate Base Weights for the 2007 Assessment

The calculation of the student-level replicate base weights differed by whether a student was in a school selected with certainty or not, since replicates were formed using first-stage sample units. The first-stage sample unit was the student in certainty schools and the school itself for noncertainty schools.

For students in certainty schools, where replicate strata were formed at the student-level by grouping students into pairs or triplets, student base weights were calculated for each of the 62 replicates based on this grouping. For students in replicate strata comprising pairs of students, the student-level replicate base weights, STU_BWT_{jsk}(r), r = 1,..., 62, were calculated as follows:

where

STU_BWT

_{jsk}is the full-sample student base weight for student*k*in certainty school*s*in stratum j,R

_{jsr}is the set of students within the r-th replicate stratum for certainty school s in stratum j, andU

_{jsk}is the variance unit (1 or 2) for student k in certainty school s in stratum j.

For students in replicate strata comprising three students, two sets of student-level replicate base weights were computed (see replicate variance estimation for details): one for the first replicate r_{1} and another for the second replicate r_{2}. The two sets of student-level replicate base weights STU_BWT_{jsk}(r_{1}), r_{1} = 1,..., 62 and STU_BWT_{jsk}(r_{2}), r_{2} = 1,..., 62 were calculated as described below.

where

- STU_BWT
_{jsk}is the full-sample student base weight for student k in certainty school s in stratum j,

_{ }is the set of students within the r_{1}-th replicate stratum for certainty school s in stratum j,- is the set of students within the r
_{2}-th replicate stratum for certainty school s in stratum j, and - U
_{jsk}is the variance unit (1, 2 or 3) for student k in certainty school s in stratum j.

For students in noncertainty schools, where replicate strata were formed at the school-level, the student base weight for student k from school s in stratum *j* for each of the 62 replicates STU_BWT_{jsk} (r), r = 1,..., 62*,* were calculated as follows:

where

SCH_BWT

_{js}(r) is the replicate school base weight;SCHSESWT

_{js}is the school-level session assignment weight used in the full-sample weight;WINSCHWT

_{js}is the within-school student sampling weight used in the full-sample weight;STUSESWT

_{jsk}is the student-level session assignment weight used in the full-sample weight;SUBJFAC

_{js}is the subject factor used in the full-sample weight;SUBADJ

_{js}is the substitute adjustment factor used in the full-sample weight; andYRRND_AF

_{js}is the year-round adjustment factor used in the full-sample weight.

Last updated 19 May 2010 (GF)

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