Final participation, exclusion, and accommodation rates were presented in quality control tables for each age and subject by reporting group. School-level participation rates were calculated as they had been calculated for previous assessments and according to National Center for Education Statistics (NCES) standards.
School-level participation rates were below 85 percent for private schools at all three ages. Student-level participation rates were all above 85 percent. As required by NCES standards, nonresponse bias analyses were conducted on each reporting group falling below the 85 percent participation threshold.