A Polytomous Model of Cognitive Diagnostic Assessment for Graded Data

Pursuing the line of the difference models in IRT (Thissen &; Steinberg, 1986 Thissen, D., &; Steinberg, L. (1986). A taxonomy of item response models. Psychometrika, 51:567–577. doi:10.1007/BF02295596.[Crossref], [Web of Science ®] , [Google Scholar]), this article proposed a new cognitive diagnostic model for graded/polytomous data based on the deterministic input, noisy, and gate (Haertel, 1989 Haertel, E. H. (1989). Using restricted latent class models to map the skill structure of achievement items. Journal of Educational Measurement, 26, 333–352. doi:10.1111/j.1745-3984.1989.tb00336.x.[Crossref], [Web of Science ®] , [Google Scholar]; Junker &; Sijtsma, 2001 Junker, B. W., &; Sijtsma, K. (2001). Cognitive assessment models with few assumptions, and connections with nonparametric item response theory. Applied Psychological Measurement, 25, 258–272. doi:10.1177/01466210122032064.[Crossref], [Web of Science ®] , [Google Scholar]), which is named the DINA model for graded data (DINA-GD). We investigated the performance of a full Bayesian estimation of the proposed model. In the simulation, the classification accuracy and item recovery for the DINA-GD model were investigated. The results indicated that the proposed model had acceptable examinees' correct attribute classification rate and item parameter recovery. In addition, a real-data example was used to illustrate the application of this new model with the graded data or polytomously scored items.