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NAEP Technical DocumentationSample Design for the 2015 State Assessment


Target Population

Sampling Frame

Stratification of Schools

School Sample Selection

Ineligible Schools 

Student Sample Selection 

School and Student Participation

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Each assessment cycle, a sample of students in designated grades within both public and private schools throughout the United States is selected for assessment. In state assessment years, of which 2015 is an example, the samples of public schools and their students in each state are large enough to support state-level estimates.

The NAEP 2015 state assessments covered fourth- and eighth-grade students in public schools for operational mathematics, reading, and science. A representative sample of students was drawn in each participating jurisdiction, including the 50 states, the District of Columbia, Puerto Rico, Bureau of Indian Education (BIE) schools, Department of Defense Education Activity (DoDEA) schools, and in school districts chosen for the Trial Urban District Assessment (TUDA) study. 

All jurisdictions, including the TUDA districts, were included in the mathematics and reading assessments, with the exception of Puerto Rico, where a special mathematics assessment was conducted instead of the operational mathematics and reading assessments. Science assessments were conducted in all non-TUDA jurisdictions with the exception of Alaska, California, Colorado, Lousiana, Pennsylvania, District of Columbia, and BIE schools.

Generally for the state assessments, each non-TUDA jurisdiction sample is designed to produce aggregate estimates with approximately equal precision for all the participating jurisdictions, as well as estimates for various subpopulations of interest. The target student sample size for these jurisdictions is 2,200 for each operational subject. In 2015, the samples for operational mathematics and reading at grades 4 and 8 were designed in this fashion.

At grades 4 and 8, the overall target assessed student sample size for the operational samples in each non-TUDA jurisdiction that signed on for science was 6,600: 2,200 each for mathematics, reading, and science. With the exception of California, for DC, BIE, and jurisdictions not signed on for science, the overall target assessed student sample size was 4,620: 2,200 each for mathematics and reading, and 220 for science.  Although California did not sign on for science, to ensure that the national science sample requirement was met, the target assessed student sample size for the science assessment in California was 2,200. For the special mathematics assessment in Puerto Rico, the target assessed student sample size was 5,750 at grades 4 and 8.

The target population for the NAEP 2015 state assessment included students in public schools who were enrolled in grades 4 and 8 at the time of assessment. The sampling frame included public schools having the relevant grade in each jurisdiction. The samples were selected based on a two-stage sample design:

  • selection of schools within participating jurisdictions; and
  • selection of students within schools.

From the stratified frame of public schools for each grade within each jurisdiction, a systematic random sample of grade-eligible schools was drawn with probability proportional to a measure of size based on the estimated grade-specific enrollment of the school.

For the TUDA study, schools were sampled from the 21 participating TUDA districts at the same time schools were selected for the jurisdiction samples. The TUDA districts are listed below:

  • Albuquerque Public Schools, New Mexico;
  • Atlanta Public Schools, Georgia;
  • Austin Independent School District, Texas;
  • Baltimore City Public Schools, Maryland;
  • Boston Public Schools, Massachusetts;
  • Charlotte-Mecklenburg Schools, North Carolina;
  • Chicago Public Schools, Illinois;
  • Cleveland Metropolitan School District, Ohio;
  • Dallas Independent School District, Texas;
  • Detroit Public Schools, Michigan;
  • Duval County District, Florida;
  • District of Columbia Public Schools, District of Columbia;
  • Fresno Unified School District, California;
  • Hillsborough County Public Schools, Florida;
  • Houston Independent School District, Texas;
  • Jefferson County Public Schools (Louisville), Kentucky;
  • Los Angeles Unified School District, California;
  • Miami-Dade County Public Schools, Florida;
  • New York City Department of Education, New York;
  • School District of Philadelphia, Pennsylvania; and
  • San Diego Unified School District, California.

These subsamples affected the design of the state samples in those states where TUDA districts were oversampled. In each of these states, there were distinct sampling rates for each TUDA district and for the balance of the state (i.e., the rest of the state not in a TUDA district).

Each selected school provided a list of eligible enrolled students from which a systematic sample of students was drawn. In fourth- and eighth-grade schools that were in non-TUDA jurisdictions that signed on for science and for California, 90 students, if possible, were selected from each school: 30 for mathematics, 30 for reading, and 30 for science. For DC, BIE, and jurisdictions not signed on for science, 63 students, if possible, were selected from each school: 30 for mathematics, 30 for reading, and 3 for science. Details can be found in the student sample selection

Last updated 17 June 2021 (SK)