A response time-based mixture item response theory model for dynamic item-response strategies.

Educational researchers have a long-lasting interest in the strategies examinees employ when responding to items in an assessment. Mixture item response theory (IRT) modeling is a popular class of approaches to studying examinees' item-response strategies. In the present study, we introduce a response time (RT)-based mixture IRT model for flexible modeling of examinee-and-item-specific item-response strategies. We posit that examinees may alternate between ability-based and non-ability-based strategies across different test items. Our proposed model identifies such within-examinee strategy switches without the need to predefine the non-ability-based strategies. Instead, our proposed approach allows for inferring the nature of these strategies from model parameter estimates. We illustrated the proposed approach using empirical data from PISA 2018 Science test and evaluated it through simulation studies. We concluded the article with discussions of limitations and future research directions.