Chapter 6: Interpreting Scales Through Scale Anchoring

The major purpose of the National Assessment of Educational Progress (NAEP) is to provide a means to compare groups of students both across and within assessment years. A complementary purpose of NAEP is to provide information about what these groups of students know and can do. This purpose has been addressed using the scale anchoring techniques described in this chapter. Scale anchoring involves a statistical component that identifies items that discriminate between successive points on the proficiency scale using specific item characteristics. It also involves a consensus component in which identified items are used by subject-area and educational experts to provide an interpretation of what groups of students at or close to the selected scale points know and can do.