NAEP Technical DocumentationSelecting School Samples for the 2001 National Main Assessment

Once the measures of size had been assigned, the actual school sample from the school frame for each grade was a systematic sample using these measures of size, with schools ordered to achieve an implicit stratification on school characteristics judged to be related to school achievement. The 2001 NAEP assessment frame ordering was the same as that of the 2000 assessment. The frame schools for each grade were ordered first by dividing into three subsets:

certainty primary sampling unit (PSU) public schools;
certainty PSU nonpublic schools; and
noncertainty PSU schools.

The certainty PSU public schools were ordered by

NAEP region first;
type of locality second;
minority status third;
PSU stratum fourth; and
estimated grade enrollment fifth.

The certainty PSU nonpublic schools were ordered by NAEP region first, school type second (Catholic, non-Catholic religious, non-religious private), PSU stratum third, and estimated grade enrollment fourth.

The noncertainty PSU schools were ordered by PSU stratum first, and then by school type (public and nonpublic). The public schools were then ordered by type of locality first, minority status second, and estimated grade enrollment third. The nonpublic schools were ordered by school type first (Catholic, non-Catholic religious, non-religious private), and estimated grade enrollment second.

The sort order was "serpentine" at each level: an alternation of ascending to descending and descending to ascending within each higher level group. For example, for certainty PSU public schools, the sort order for estimated grade enrollment within PSU stratum was ascending to descending for the first PSU stratum, descending to ascending for the next PSU stratum, and so on.

Last updated 18 June 2008 (DR)

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