In every NAEP assessment, the student sample falls into the following groups:
Withdrawn students are those students who have left the school before the assessment data have been collected. Excluded students are those who cannot be assessed even with an accommodation because they are classified as students with disabilities (SD) or as limited-English-proficient (LEP) students. Assessed students are either assessed in the initial session, or if they were absent for that session, perhaps in the makeup session. The last category in the list includes students who were not excluded (i.e., "were to be assessed"), but were not assessed, either due to absence (from both sessions) or a refusal to participate.
Assessed students are also classified as assessed without an accommodation or assessed with an accommodation. The latter group can be divided into SD students assessed with an accommodation, LEP students assessed with an accommodation, or students who are both SD and LEP and accommodated (students neither SD nor LEP can only be assessed without an accommodation). Note that some SD and LEP students are assessed without accommodations.