​NAEP Technical DocumentationSchool Base Weights

The school base weight for a sampled school is equal to the inverse of its overall probability of selection. The overall selection probability of a sampled school differs by the type of sampled school (original or substitute) and by the type of sampling frame (new school frame or not).

The overall selection probability of an originally selected school in a civics, mathematics, reading, or U.S. history sample is equal to its probability of selection from the NAEP public/private school frame.

The overall selection probability of a school from the new school frame in a civics,  mathematics, reading, or U.S. history sample is the product of two quantities:

  • the probability of selection of the school's district into the new-school district sample or the Catholic diocese into the new-school Catholic diocese sample, and
  • the probability of selection of the school into the new school sample.

The new-school district sampling procedures for the 2022 national public school samples for the civics and U.S. history assessment at grade 8 are very similar to the new-school district sampling procedures for the 2022 state public schools assessments in mathematics and reading.

New-school Catholic diocese sampling procedures for the 2022 national private school assessments for mathematics and reading at grades 4 and 8 and for civics and U.S. history at grade 8 are similar as well.

For the mathematics and reading long-term trend (LTT) assessments at ages 9 and 13, the new-school district and Catholic diocese sampling procedures took advantage of the work already being done for the grade-based assessments.   

Substitute schools are preassigned to original schools and take the place of original schools if they refuse to participate. For weighting purposes, substitute schools are treated as if they were the original schools they replaced, so substitute schools are assigned the school base weight of their corresponding original schools.

Learn more about substitute schools for the 2022 national public school assessments for civics and U.S. history at grade 8 and for mathematics and reading LTT assessments at age 9. The 2022 state public school assessment in mathematics and reading do not use substitute schools.

Learn more about substitute schools for the 2022 national private school assessments in mathematics and reading at grades 4 and 8, in civics and U.S. history at grade 8, and in mathematics and reading LTT assessments at ages 9 and 13.

Last updated 18 July 2024 (SK)