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About the Assessment: Target Population and Sample Size

The schools and students participating in NAEP assessments are selected to be representative of all schools nationally and of public schools at the state level. Samples of schools and students are drawn from participating states and from the District of Columbia and Department of Defense schools.  While results for students assessed in Alaska, the District of Columbia, Kansas, Nebraska, and Vermont contributed to the results for the nation at grades 4 and 8, sample sizes were not large enough to report results for these states/jurisdictions separately. At grades 4 and 8, the results from the assessed students are combined to provide accurate estimates of the overall performance of students in the nation and in individual states and other jurisdictions. States with districts participating in the Trial Urban District Assessments have larger sample sizes.

While national results reflect the performance of students in both public schools and nonpublic schools (i.e., private schools, Bureau of Indian Education schools, and Department of Defense schools), state-level results reflect the performance of public school students only. Results are reported separately for Department of Defense schools in state tables and maps. More information on sampling can be found in NAEP Technical Documentation.

The sample of students in the participating TUDA school districts is an extension of the sample of students who would usually be selected by NAEP as part of state and national samples. Results for students in the TUDA samples are also included in state and national samples with appropriate weighting. For example, the results reported for students in Boston also contribute to the results reported for Massachusetts and to the results for the nation.

National and State
Student sample sizes and target populations in NAEP science at grade 4, by district: 2009
District Sample size Target population
Nation (public) 155,000 3,485,000
Large city 35,700 572,000
Atlanta 1,200 4,000
Austin 1,600 6,000
Baltimore City 1,200 6,000
Boston 1,200 4,000
Charlotte 1,600 10,000
Chicago 2,000 29,000
Cleveland 1,000 3,000
Detroit 900 6,000
Fresno 1,400 5,000
Houston 2,300 15,000
Jefferson County (KY) 1,500 7,000
Los Angeles 2,200 48,000
Miami-Dade 2,200 24,000
Milwaukee 1,300 6,000
New York City 2,200 71,000
Philadelphia 1,300 13,000
San Diego 1,300 9,000
NOTE: The sample size is rounded to the nearest hundred. The target population is rounded to the nearest thousand.
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2009 Science Assessment.