A Polytomous Extension of the Generalized Distance Discriminating Method

Abstract

This article proposes a generalized distance discriminating method for test with polytomous response (GDD-P). The new method is the polytomous extension of an item response theory (IRT)-based cognitive diagnostic method, which can identify examinees' ideal response patterns (IRPs) based on a generalized distance index. The similarities between observed response patterns and IRPs for polytomous response situation are measured by the index of GDD-P, and the attribute patterns can be recognized via the relationship between attribute patterns and IRPs. Feasible designs about polytomous Q-matrix and scoring items for polytomous response are also discussed. In simulation, the classification accuracy of the GDD-P method for the test with polytomous response was investigated, and results indicated that the proposed method had promising performance in recognizing examinees' attribute patterns. © The Author(s) 2013.