​NAEP Technical DocumentationSampling Frame for the 2020 Public School Long-Term Trend Assessment

			Age Distribution Fractions New-School Sampling Frame

Drawing the school samples for the 2020 assessment required a comprehensive list of public schools in each jurisdiction containing information for stratification purposes. As in previous NAEP assessments, the Common Core of Data (CCD) file developed by NCES was used to construct the sampling frame. The CCD file corresponding to the 2017-2018 school year provided the frame for all regular public (as classified by the CCD), state-operated public (as classified by the CCD), Bureau of Indian Education (BIE), and Department of Defense Education Activity (DoDEA) schools in the 50 states and the District of Columbia.

The sampling frame was restricted to schools located in the primary sampling units (PSUs) selected for the NAEP 2020 long-term trend (LTT) assessment. In addition, the sampling frame excluded ungraded schools, vocational schools with no enrollment, special-education-only schools, homeschool entities, prison or hospital schools, and juvenile correctional institutions. Vocational schools with no enrollment serve students who split their time between the vocational school and their home school.

The public school frame for the LTT assessment for age 9 contained approximately 29,000 schools. The estimated age 9 enrollment (unweighted) for these schools was 2.21 million and the estimated age 9 enrollment (weighted) was 3.78 million. The public school frame for the LTT assessment for age 13 contained approximately 26,000 schools. The estimated age 13 enrollment (unweighted) for these schools was 2.20 million and the estimated age 13 enrollment (weighted) was 3.76 million. The unweighted estimated enrollments are restricted to the selected PSUs for LTT. The weighted estimated enrollments incorporate the PSU weight (inverse of the probability of selecting the PSU), and thus are national estimates of the number of public school students for each age population. The age-eligible enrollment was estimated using age distribution fractions (see link above right) derived by grade for each age population.

For quality control purposes, school and student counts from the sampling frame were compared to school and student counts from previous public school frames by grade. No major discrepancies were found.

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