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NAEP Sample Design → Sample Design for the 2000 Assessment → National Main Assessment Sample Design in 2000 → Sampling of Schools in the 2000 National Main Assessment → Assigning Measure of Size and Selecting School Samples for the 2000 National Main Assessment → Grade 4 and 12 Public School Samples for the 2000 National Main Assessment

NAEP Technical DocumentationGrade 4 and 12 Public School Samples for the 2000 National Main Assessment

Grade 4 and 12 public school samples were similar to past national main designs. The actual school sample from the school frame for each grade was a systematic sample using the assigned measures of size. Schools in the frame for each grade were ordered first by dividing into two subsets: certainty PSU schools and noncertainty PSU schools. The certainty PSU schools were ordered as follows:

1. NAEP region;

2. locale (locale is a Common Core of Data (CCD) field attached to each school defining the type of locality of the community: central city large city, central city mid-sized city, urban fringe large city, urban fringe mid-sized city, large town, small town, rural (note that the two CCD rural groups are collapsed together here);

3. minority status, whether the school was designated as high minority;

4. PSU stratum (see Assigning Measure of Size and Selecting School Samples for a definition of the PSU strata);

5. school type (school type for public schools includes the categories: regular, state-run, Bureau of Indian Affairs (BIA), and the Department of Defense's Domestic Dependent Elementary and Secondary Schools (DDESS); and

6. estimated grade enrollment, which approximates the number of students enrolled in the assessed grade.

The noncertainty PSU schools were ordered by PSU stratum first, type of locality second, minority status third, school type fourth, and estimated grade enrollment fifth. The sort order was "serpentine" at each level: an alternation of ascending to descending and descending to ascending within each higher level group (e.g., for certainty PSU public schools, the sort order for estimated grade enrollment within school type was ascending to descending for the first school type, descending to ascending for the next school type). This sort order is designed to ensure that adjacent schools in the sorted list have similar characteristics, even at variable cut points.

For the grade 4 and 12 public school samples, the number of schools to be selected was not determined separately for each PSU in the national main samples. Instead, an overall sample size was determined so that the national target number of students to be assessed would be selected (adjusted for nonparticipation of schools and students and exclusion of students) and that the probability of selection of a student would be uniform over the United States (exceptions are students from very small schools and high minority schools), given that all students in schools with fewer than a specified number of eligible students would be selected and that only this specified number of students would be selected in larger schools.

The number of schools selected for the grade 4 and 12 public school samples were 575 and 320 schools, respectively. They were based on a target sample of 29,500 students at grade 4 and 16,000 students at grade 12. These samples were inflated to 41,500 and 28,000, respectively, to offset student attrition due to school ineligibility, student exclusion, and student nonresponse. The inflation factors used in 2000, as shown below, were based on experience with the national main NAEP sample.

Inflation factor used to offset attrition in public school student participation, by school type and grade, the national main assessment: 2000

Grade	School type	Inflation factor
4	Catholic	1.062
	Other	1.333
8	Catholic	1.075
	Other	1.449
12	Catholic	1.161
	Other	1.783
NOTE: The inflation factor is an inverse of participation. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2000.

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