A Comparison of Polytomous Rasch Models for the Analysis of C-Tests

Document Type : Original Research Article


1 English Language Department, Al-Mustaqbal University College, Babylon, Iraq

2 University of Warith Al-Anbiyaa, Karbala, Iraq

3 Al-Nisour University College/Baghdad/Iraq

4 Al-Manara College for Medical Sciences (Maysan)/Iraq

5 Department of Medical Laboratory Technics, Al-Zahrawi University College, Karbala, Iraq

6 Nursing Department, Hilla University College, Babylon, Iraq.

7 Altoosi University College, Najaf, Iraq

8 Al-Esraa University College, Baghdad, Iraq


A C-Test is a gap-filling test for measuring language competence in the first and second language. C-Tests are usually analyzed with polytomous Rasch models by considering each passage as a super-item or testlet. This strategy helps overcome the local dependence inherent in C-Test gaps. However, there is little research on the best polytomous Rasch model for C-Tests. In this study, the Rating Scale Model (RSM) and the Partial Credit Model (PCM) for analyzing C-Tests were compared. To this end, a C-Test composed of six passages with both RSM and PCM was analyzed. The models were compared in terms of overall fit, individual item fit, dimensionality, test targeting, and reliability. Findings showed that, although the PCM has a better overall fit compared to the RSM, both models produce similar test statistics. In light of the findings of the study, the choice of the best Rasch model for C-Tests will be discussed.