In addition to the full-sample weight, a set of replicate weights was provided for each student. These replicate weights are used in calculating the sampling variance of estimates obtained from the data, using the jackknife repeated replication method. The method of deriving these weights was aimed at reflecting the features of the sample design appropriately in each jurisdiction, so that when the jackknife variance estimation procedure is implemented, approximately unbiased estimates of sampling variance are obtained. This page gives the specifics for generating the replicate weights for the 2002 main study assessment samples. The theory that underlies the jackknife variance estimators used in NAEP studies is discussed on the web page Replicate Variance Estimation.
In each sample, replicates were formed in two steps. First, each school was assigned to one or more of 62 replicate strata. In the next step, a random subset of schools (or, in some cases, students within schools) in each replicate stratum was excluded. The remaining subset and all schools in the other replicate strata then constituted one of the 62 replicates.
The computation of replicate weights includes