Skip Navigation
small NCES header image

Table of Contents  |  Search Technical Documentation  |  References

NAEP Weighting Procedures → Weighting Procedures for the 2005 Assessment → Computation of Replicate Weights for the 2005 Assessment → Computing Student-Level Replicate Base Weights for the 2005 Assessment

Computing Student-Level Replicate Base Weights for the 2005 Assessment

For the 2005 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_BWTjsk(r), r = 1,..., 62, were calculated as follows:

STU underscore BWT subscript jsk open paren r close paren equals open paren two times STU underscore BWT subscript jsk for jsk is an element of cap R subscript jsr and cap U subscript jsk equals one close paren or equals open paren zero for jsk is an element of cap R subscript jsr and cap U subscript jsk equals two close paren or equals open paren STU underscore BWT subscript jsk if jsk is not an element of cap R subscript jsr

where

  • STU_BWTjsk is the full-sample student base weight for student k in certainty school s in primary stratum j,

  • Rjsr is the set of students within the r-th replicate stratum for certainty school s in primary stratum j, and

  • Ujsk is the variance unit (1 or 2) for student k in certainty school s in primary 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 r1 and another for the second replicate r2. The two sets of student-level replicate base weights STU_BWTjsk(r1), r1 = 1,..., 62, and STU_BWTjsk(r2), r2 = 1,..., 62, were calculated as described below.  

STU underscore BWT subscript jsk open paren r subscript one close paren equals open paren one point five times STU underscore BWT subscript jsk for jsk is an element of cap R subscript jsr subsubscript one and cap U subscript jsk equals one close paren or equals open paren one point five times STU underscore BWT subscript jsk for jsk is an element of cap R subscript jsr subsubscript one and cap U subscript jsk equals two close paren or equals open paren zero for jsk is an element of cap R subscript jsr subsubscript one and cap U subscript jsk equals three close paren or equals open paren STU underscore BWT subscript jsk for jsk is not an element of cap R subscript jsr subsubscript one close paren

STU underscore BWT subscript jsk open paren r subscript two close paren equals open paren one point five times STU underscore BWT subscript jsk for jsk is an element of cap R subscript jsr subsubscript two and cap U subscript jsk equals one close paren or equals open paren zero for jsk is an element of cap R subscript jsr subsubscript two and cap U subscript jsk equals two close paren or equals open paren one point five times STU underscore BWT subscript jsk for jsk is an element of cap R subscript jsr subsubscript two and cap U subscript jsk equals three close paren or equals open paren STU underscore BWT subscript jsk if jsk is not an element of cap R subscript jsr subsubscript two close paren

 

For students in noncertainty schools, where replicate strata were formed at the school-level, student base weights for each of the 62 replicates STU_BWT(r), r = 1, ..., 62, were calculated as follows:  

   STU underscore BWT left parenthesis r right parenthesis equals SCH underscore BWT left parenthesis r right parenthesis times SCHSESWT times WINSCHWT times STUSESWT times SUBJFAC times SUBADJ times YRRND underscore AF

where

  • SCH_BWT(r) is the replicate school base weight;

  • SCHSESWT is the school-level session assignment weight used in the full-sample weight;

  • WINSCHWT is the within-school student sampling weight used in the full-sample weight;

  • STUSESWT is the student-level session assignment weight that reflects the conditional probability, given the particular assessment type was assigned to the school, that the student was assigned to that assessment type

  • SUBJFAC is the subject factor used in the full-sample weight

  • SUBADJ is the substitute adjustment factor used to account for the difference in enrollment size between the substitute and original school; and

  • YRRND_AF is the year-round adjustment factor used in the full-sample weight.


Last updated 08 May 2009 (EH)

Printer-friendly Version


Would you like to help us improve our products and website by taking a short survey?

YES, I would like to take the survey

or

No Thanks

The survey consists of a few short questions and takes less than one minute to complete.
National Center for Education Statistics - http://nces.ed.gov
U.S. Department of Education