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Understanding Assessment Results

NAEP Achievement Levels

When reviewing the results from the National Assessment of Educational Progress (NAEP), it is helpful to understand how student performance is reported. Since NAEP is not designed to report results for individual students or schools, it is not necessary for every student in the nation to take the assessment. Instead, NAEP is administered to a sample of students in grades 4, 8, and 12, who represent the student population of the nation, states, and districts.

Because assessment results are based on samples of students, there are a number of factors to consider when drawing conclusions about NAEP data. Consult this useful guide to understand and interpret reports data. Guides on how to understand specific assessments (e.g. mathematics, reading, etc.) are also accessible in this section.

How Results Are Reported: Scale Scores and Achievement Levels

Student performance on NAEP assessments is presented in two ways: 

  1. Average scale scores represent how students performed on each assessment. Scores are aggregated and reported at the student group level for the nation, states, and districts. They can also be used for comparisons among states, districts, and student groups.
  2. Achievement levels are performance standards that describe what students should know and be able to do. Results are reported as percentages of students performing at or above three achievement levels (Basic, Proficient, and Advanced). Students performing at or above the Proficient level on NAEP assessments demonstrate solid academic performance and competency over challenging subject matter. It should be noted that the NAEP Proficient achievement level does not represent grade level proficiency as determined by other assessment standards (e.g., state or district assessments).

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Student Groups

Results are provided for groups of students defined by shared characteristics—race/ethnicity, gender, eligibility for free/reduced-price school lunch, highest level of parental education, type of school, charter school, school location, region of the country, status as students with disabilities (SD), and/or status as English language learners (ELL).

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Sample Size and Statistical Significance

Statistical Significance

Scores among groups of students may or may not be meaningful, depending on whether or not they are statistically significant. The numbers of students who participate in an assessment determines what performance differences across years or among groups are statistically significant. As a sample size increases, smaller differences between years or groups are found to be more statistically significant than would have been detected in a smaller sample size.

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Exclusion Rates

Some SD and ELL students may be able to participate in NAEP, with or without accommodations. Others are excluded from NAEP assessments because they cannot participate with allowable accommodations. The percentage of SD and ELL students who are excluded from the NAEP assessments varies both from one jurisdiction to another and within a jurisdiction over time.

Subject-Specific Guides

Explore guides on how to understand specific assessments, by subject.


Last updated 28 March 2018 (AA)