Unidimensionality or Multidimensionality: The Application of Item Response and Testlet Response Models in a Mixed-Format Reading Proficiency Test

• In Event: 26.069 - Rasch Model-Specific Applications and Their Impact in Research

Abstract

This study investigated the parameter recovery precision for mixed-format reading proficiency tests under different variances of testlet effects using standard Rasch Model (IRT) and Rasch Testlet Model (TRT). Results from the study showed that under TRT model, the recovered parameters for both dichotomous and polytomous items had a tendency to shrink towards the mean. Using IRT model to fit testlet-based response data resulted in a significantly larger RMSE for item parameter estimates. However, no significant differences were discovered for θ recovery under the two models with different ability groups.

Authors

• Lihong Yang, Michigan State University

• Mingcai Zhang, Michigan State University