ABSTRACT
There are many reasons for the increase of interest in diagnostic testing. One reason is that well-designed diagnostic tests can provide very detailed assessments of achievement in academic domains. In such applications, the goal is not to provide a single number summarizing a student’s geometry achievement, for example, but to separately assess the student’s ability to answer various specific types of geometry problems, say, problems that deal with the congruence of two triangles or that involve applying a specific theorem. The results of such diagnostic tests might be used to design effective interventions for individual students, or be combined across students in order to evaluate particular curricula. In either case, the value of the diagnostic test arises from the fact that such a test provides not a single numeric index of overall skill of a student, but rather describes the student’s specific pattern of mastered and nonmastered subskills.
