Relationships and Properties of Polytomous Item Response Models

http://come.to/nirt
Van der Ark, L. A. (2001). Relationships and properties in polytomous item response theory models. Applied Psychological Measurement, 25, ??-??.

Overview of relationships

Input files

To start my research in polytomous IRT I investigated 20 popular polytomous IRT models and 10 measurement properties. The 30 × 29 = 870 relationships among these models and properties are discussed in a working paper (Van der Ark, 1999). It is impossible to publish such an overload of theorems, examples, definitions, and implications in a regular journal. An overview will be published in a special issue of Applied Psychological Measurement on nonparametric IRT (Van der Ark, 2001). This paper gives the relationships without any proof, and discusses some applications. For those interested in the relationships discussed in this paper, I built this website.

First, contains a large table of relationships. Clicking on each cell in the table shows the proof of the relationship.
Second, it contains input filesof the computer program LEM ( Vermunt, 1997) used to estimate the model parameters of some of the discussed models.