In order to determine the effect of using different criteria for excluding students from the assessment, two different sample types (S2 and S3) were assigned to the schools sampled for the U.S. history and geography study. In sample type 3 schools, accommodations were offered students with disabilities (SD) and limited-English-proficient (LEP) students who met the criteria for inclusion in the assessment. In sample type 2 schools, no assessment accommodations were offered to SD/LEP students.
Sample type was assigned to schools separately for each grade so that 50 percent of the schools were assigned sample type 2 and 50 percent were assigned sample type 3. It should be noted that schools which were sampled for more than one grade were assigned only one sample type, which was used then for all sampled grades.