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Computing School-Level Replicate Base Weights for the 2006 Assessment

For the NAEP 2006, school-level replicate base weights for school s in primary stratum j (SCH_BWTjs(r), r = 1,..., 62) were calculated as follows:

                       

SCH underscore BWT subscript js, into bracket r subscript 2, bracket closes, equals left brace 3 rows, 3 column matrix,row 1 column 1 is: 2 times SCH underscore BWT subscript js, row 1 column 2 is: for js is an element of R subscript jr, row 1 column 3: U subscript js equals 1.

where

  • SCH_BWTjs is the school base weight for school s in primary stratum j,

  • Rjr is the set of schools within the r-th replicate stratum for primary stratum j, and

  • Ujs is the variance unit (1 or 2) for school s in primary stratum j.

For schools in replicate strata comprising three variance units, two sets of school-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 school-level replicate base weights, SCH_BWTjs(r1), r1 = 1,..., 62 and SCH_BWTjs(r2), r2 = 1,..., 62, were calculated as described below.  

                       

SCH underscore BWT subscript j s open paren r subscript 1 close paren equals open paren one point five times SCH underscore BWT subscript j s for j s is an element of cap r subscript j r subscript 1 and cap u subscript j s equals one close paren or equals open paren one point five times SCH underscore BWT subscript j s for j s is an element of cap r subscript j r subscript 1 and cap u subscript j s equals two close paren or equals open paren zero for j s is an element of cap r subscript j r subscript 1 and cap u subscript j s equals three close paren or equals open paren SCH underscore BWT subscript js if j s is not an element of cap r subscript j r subscript 1

 

SCH underscore BWT subscript j s open paren r subscript two close paren equals open paren one point five times SCH underscore BWT subscript j s for j s is an element of cap r subscript j r subsubscript two and cap u subscript j s equals one close paren or equals open paren zero for j s is an element of cap r subscript j r subsubscript two and cap u subscript j s equals two close paren or equals open paren one point five times SCH underscore BWT subscript j s for j s is an element of cap r subscript j r subsubscript two and cap u subscript j s equals three close paren or equals SCH underscore BWT subscript j s if j s is not a member of cap r subscript j r subsubscript two

where

  • SCH_BWTjs is the school base weight for school s in primary stratum j,

  • cap r subscript j r subscript 1 is the set of schools within the r1-th replicate stratum for primary stratum j,

  • cap r subscript j r subscript 2 is the set of schools within the r2-th replicate stratum for primary stratum j, and

  • Ujs is the variance unit (1, 2 or 3) for school s in primary stratum j


Last updated 12 April 2010 (GF)

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National Center for Education Statistics - http://nces.ed.gov
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