NAEP is designed to measure the academic performance of the nation’s students at grades 4, 8, and 12. But NAEP can’t really test every fourth-, eighth-, and twelfth-grader in the country, because it would take up far too much time in schools across the nation. So instead of testing everyone, NAEP selects a small sample that accurately represents the characteristics of the students in the nation, including ethnicity, school size, economic background, gender, and more.
If your school was selected for the NAEP assessment, it is because it is “statistically representative” of your state’s schools. And if you were selected for NAEP, it’s because you were chosen at random to represent the nation’s students. Test-takers are selected randomly to try to ensure that the group taking the test is the most representative of the entire student body of the school.