GRAPHICAL REPRESENTATION OF MULTIDIMENSIONAL ITEM RESPONSE THEORY ANALYSES

This paper illustrates how graphical analyses can enhance the interpre tation and understanding of multidimensional item response theory (IRT ) analyses. Many unidimensional IRT concepts, such as item response fu nctions and information functions, can be extended to multiple dimensi ons; however, as dimensionality increases, new problems and issues ari se, most notably how to represent these features within a multidimensi onal framework. Examples are provided of several different graphical r epresentations, including item response surfaces, information vectors, and centroid plots of conditional two-dimensional trait distributions . All graphs are intended to supplement quantitative and substantive a nalyses and thereby assist the test practitioner in determining more p recisely such information as the construct validity of a test, the deg ree of measurement precision, and the consistency of interpretation of the number-correct score scale.