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 each state and from the District of Columbia and Department of Defense schools. 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.

For grade 12, the schools and students participating in NAEP assessments were selected to be representative of all schools nationally and of public schools at the state level in the eleven participating states. There are more public school students selected from the eleven participating states than the non-participating states to provide accurate estimates of the performance of students in those individual states. Proper weighting techniques were applied to insure accurate estimates of the overall performance of students in the nation as well.

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 also 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 Trial Urban District Assessment (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.

Student sample sizes and target populations in NAEP mathematics at grade 8, by district: 2009
District	Sample size	Target population
Atlanta	900	3,000
Austin	1,400	5,000
Baltimore City	1,000	4,000
Boston	1,200	4,000
Charlotte	1,400	9,000
Chicago	1,900	28,000
Cleveland	1,000	3,000
Detroit	1,100	6,000
District of Columbia (DCPS)	900	2,000
Fresno	1,400	5,000
Houston	2,000	12,000
Jefferson City (KY)	1,500	7,000
Los Angeles	2,100	48,000
Miami-Dade	2,100	23,000
Milwaukee	1,000	5,000
New York City	2,200	69,000
Philadelphia	1,300	11,000
San Diego	1,100	8,000
NOTE: The sample size is rounded to the nearest hundred. The target population is rounded to the nearest thousand. DCPS = District of Columbia Public Schools. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2009 Mathematics Assessment.

Learn more about the sampling design.