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Application of a General Polytomous Testlet Model to the Reading Section of a Large-Scale English Language Assessment IRT

Author(s):
Li, Yanmei; Li, Shuhong; Wang, Lin
Publication Year:
2010
Report Number:
RR-10-21
Source:
ETS Research Report
Document Type:
Report
Page Count:
34
Subject/Key Words:
Item Response Theory (IRT), Local Item Dependence, Polytomously Scored Items, Reliability

Abstract

Results based on both simulated and real data suggested that local dependence had a small impact on item parameter estimates and a relatively larger impact on test information and reliability. It was also found that the multidimensional IRT model with simple structure fit the real data sets better than the general polytomous testlet model and the standard IRT model did.

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