Methodology: Mapping State Standards onto the NAEP Scales

The percentage of students identified as proficient on state assessments varies across states. Because each state’s standard for proficient performance is set independently, the standards in different states can be quite different, even though they use the similar terminology. There is no assurance that students who meet the standards of one state would be able to meet the standards of another state, so the effectiveness of schools cannot be assessed across states in terms of the percentages of students reported to meet the standards. The National Assessment of Educational Progress (NAEP), however, can provide the needed link to compare these assessment results across states.

Starting with the 2003 assessments and using NAEP as the common benchmark, the U.S. Department of Education, through its National Center for Education Statistics (NCES), has been publishing NAEP scale equivalents of each state’s standards in mathematics and reading, allowing comparison of the standards across states.

Identifying the NAEP equivalent of a state standard is simple. States report percentages meeting standards in each school to the public (except for small schools, to avoid compromising individual privacy). For the set of schools in the state that both participate in NAEP and the state test, the average percentage meeting the state standard is computed and compared to the distribution of scores on NAEP. For example, if the average percentage meeting the state standard is 47 percent, then the NAEP scale equivalent is the value on the NAEP achievement scale exceeded by 47 percent of the NAEP scores in the state. Additional information, published reports, and methodological information is available here.