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.
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.
Some charter schools that operate within the geographic boundaries of a school district are independent of the district and are not included in the districts' Adequate Yearly Progress (AYP) report to the U.S. Department of Education under the Elementary and Secondary Education Act. Beginning in 2009, charter schools of this type are no longer included in the results for TUDA districts as they had been in past NAEP assessments.
School districts vary in whether the charter schools within their boundaries are independent of the districts. Prior to 2009, charter schools were included in the TUDA district results if they were listed as part of the district’s Local Education Agency in the NCES Common Core of Data. Beginning in 2009, charter schools were included in TUDA district results if they contributed to the district’s AYP results as part of the Elementary and Secondary Education Act.