Toward a Psychometrics for Testlets

In 1987 the testlet was introduced as one way of dealing with a variety of problems that might occur with the algorithmic construction of tests. In the short time since its introduction, its range of plausible usages has been broadened considerably through the work of other researchers. In this paper we examine three different applications of the testlet concept and describe the psychometric models which seem most suitable for each application. In each case, the testlet concept gracefully solves a problem that would have been awkward with other, more traditional approaches.