NAEP State Assessment Sample Design Frequently Asked Questions

NAEP provides results on student achievement, instructional experiences, and school environment factors for the nation, states, and participating urban districts. Since NAEP is not designed to report results for individual students or schools, it is not necessary for every student in every school to take the assessment. Instead, an accurate picture of student performance is obtained by administering NAEP to a sample of students who represent the student population of the nation as a whole and of individual states and districts participating in Trial Urban District Assessment (TUDA).

To ensure that a representative sample of students is assessed, NAEP is given in a sample of schools whose students reflect the varying demographics of a specific jurisdiction, be it the nation, a state, or a district. Within each selected school and grade to be assessed, students are chosen at random to participate in NAEP. Every student has the same chance of being chosen—regardless of race/ethnicity, socioeconomic status, disability, status as an English learner, or any other factors.

It is important that all selected schools and students participate in NAEP. Participation is vital for valid information about the performance of students across the country to be collected and shared. Elected officials, policymakers, and educators all use NAEP results to develop ways to improve education.

The following steps are used to select a sample of public schools in a year when NAEP reports state-level results. Private schools are not included in a state-level sample, which focuses solely on public schools.

1. Identify schools

Schools are identified based on the U.S. Department of Education’s public school system database. Because national-level data on schools can be up to three years old, school data is verified with state departments of education. A national sample of nonpublic (private) schools is also selected for grades 4, 8, and 12.

2. Classify schools

Schools are classified into groups by type of location (city, suburb, town, or rural) and then by racial/ethnic composition. These groups are called strata.

3. Arrange schools

Schools are sorted by a student achievement measure (e.g., school-level results on state achievement tests) to ensure NAEP represents all levels of school performance.

4. List schools

The school groupings are then placed into a comprehensive ordered list. The specific schools that comprise the sample are ordered based on location type, race/ethnicity, and student achievement.

5. Select schools

NCES draws a separate sample of schools from each stratum with probability proportional to school size. Small schools, high minority schools, and private schools are sampled to ensure that they are adequately represented.

If the school participation rate in the sample is below 85 percent, the results cannot be reported.

6. Confirm schools

A list of selected schools is sent to each state department of education to confirm eligibility. School closure or no eligible students would prevent a school from being selected.

Learn more about how NAEP selects schools NAEP assessments in Focus on NAEP: Sampling for NAEP Assessments.

Once a school has been selected for either a state or national assessment, students within the school are selected for each subject area based on grade (4, 8, or 12). From this list, a sample of students is randomly selected by NCES to participate in the assessment. Every student in a sampled school is eligible to be selected.

After the sample is drawn, students are assigned to a single subject area in which to answer questions. In general, 30 students are selected per grade per subject from each school. Typically, 95 percent of fourth- and eighth-grade students and 85 percent of twelfth-grade students selected agree to participate.

Students with disabilities and English language learners are eligible to receive accommodations offered by the NAEP program.

Learn more about how NAEP selects students for NAEP assessments in Focus on NAEP: Sampling for NAEP Assessments.

The probability (or chance) of being selected for the NAEP state sample depends on the size of the student enrollment at each school. Generally, if a school is chosen frequently it is because the school’s enrollment in the grade constitutes a relatively large proportion of the state’s student population. Therefore, large schools are more likely to be selected than smaller ones. The sampling process is repeated each year that NAEP is administered, each time using the most recent data to account for changes in schools and shifts in student demographics across states and the nation.

For state assessments, NAEP selects for the sample around 100 public schools for each subject at each grade—each school represents about 1% of that state’s public school students in the grade being assessed. If a school is chosen repeatedly, typically that is because their enrollment in the grade represents more than 1% of the state’s enrollment in the grade. Other schools, with 0.5%-1% of the enrollment, are not always selected, but are selected very frequently.

For NAEP assessments based on state samples (mathematics, reading, science, and writing at grades 4 and 8), the samples within each state are designed (with one exception mentioned below) to be proportionately representative of all the different groups of students in the state. No students are targeted for oversampling based on their student characteristics. However, in a state that contains one or more districts that are participating in the Trial Urban District Assessment (TUDA), students from the districts involved are sampled at a greater rate than those in the remainder of the state. NAEP's weighting procedures ensure that the final results for the state are based on the correct proportional contribution from these TUDA districts despite this difference in sampling rates within the state. National samples for other subjects, for grade 12, and for private schools may require oversampling.

The number of schools and students selected to participate in NAEP varies each year, depending on the number of subjects being assessed and the level of results to be reported (i.e., national, state, or district-level).

National Results: For NAEP results to be representative of the nation, far fewer schools and students need to participate than when results for states are being reported. Within each state, the number of schools selected to participate will vary depending on the size of its student population. For example, California has a much larger share of the student population, so it is much more likely to have schools in the sample than Wyoming.

State Results: In years when NAEP also reports state-level results, larger numbers of schools are needed to ensure that the results are representative of each state’s student population. Approximately 3,000 public school students per subject and grade are assessed in each state.

District Results: The number of schools and students needed to represent the districts participating in TUDA varies, depending on the size of the district. Generally, in each district, approximately 1,500 public school students per subject and grade are assessed. These schools and students are added to and contribute to the state’s sample. While TUDA districts have a large sample, their data are combined with the state’s data proportionally so as not to over-represent the district in the overall state results.

On the Nation's Report Card website, you can see rounded numbers of the schools and students that participated in recent assessments.

The process for private school selection is similar to the public school selection process, but depends on the U.S. Department of Education’s private education system databases to create the initial list of all known private schools. Private schools are sampled to be representative of private schools nationwide. The results for private schools are not included in state-level results which are solely focused on public schools.

No. NCES selects a sample of schools using the NAEP sampling process to ensure the validity of the results. States verify if the selected schools are eligible to participate. This process ensures that NAEP assesses the most representative sample of students as possible.

The National Center for Education Statistics and the National Assessment Governing Board have established participation rate standards that states and jurisdictions are required to meet in order to have their results published. Beginning in 2003, if a state’s school response rate is below 85%, the results will not be published by NAEP, regardless of the response rate after substitution. To read details about response rates for a particular assessment, see the section on weighting procedures in the technical documentation. From this page, look to the right, and choose the year you are interested in. On the weighting procedures page for the year selected, find the link "Quality Control..." on the right, and from the page that appears, click "Nonresponse Bias Analyses."

Yes. Students are randomly selected from a list of all students enrolled in the grade that is to be assessed in each school. NAEP’s policy has always been to include as many sampled students as possible in the assessment so that results are representative of all students. NAEP offers a comprehensive array of research-based accommodations for students with disabilities, students with 504 plans, and English learners to participate in the assessment.

For the most recent assessments, find out how many students participate in the FAQs on The Nation's Report Card website. For assessments as early as 2000, to find numbers of schools and students as well as participation rates, go to NAEP technical documentation and explore the section on weighting procedures. From this page, look to the right, and choose the year you are interested in. On the weighting procedures page for the year selected, find the link "Quality Control..." on the right, and from the page that appears, click "Main Quality Control Findings of Interest."

Learn more about how NAEP selects schools and students for NAEP assessments in Focus on NAEP: Sampling for NAEP Assessments. For additional technical information on NAEP sampling, explore NAEP Assessment Sample Design.