In press, Journal of Educational & Behavioral Statistics A Sharing Item Response Theory Model for Computerized Adaptive Testing

A new sharing item response theory (SIRT) model is presented which explic-itly models the effects of sharing item content between informants and test-takers. This model is used to construct adaptive item selection and scoring rules that provide increased precision and reduced score gains in instances where sharing occurs. The adaptive item selection rules are expressed as functions of the item’s exposure rate in addition to other commonly used properties (characterized by difficulty, discrimination, and guessing para-meters). Based on the results of simulated item responses, the new item selection and scoring algorithms compare favorably to the Sympson-Hetter exposure control method. The new SIRT approach provides higher reliability and lower score gains in instances where sharing occurs. 1