An Illustration of an IRTree Model for Disengagement

Low-stakes test performance commonly reflects examinee ability and effort. Examinees exhibiting low effort may be identified through rapid guessing behavior throughout an assessment. There has been a plethora of methods proposed to adjust scores once rapid guesses have been identified, but these have been plagued by strong assumptions or the removal of examinees. In this study, we illustrate how an IRTree model can be used to adjust examinee ability for rapid guessing behavior. Our approach is flexible as it does not assume independence between rapid guessing behavior and the trait of interest (e.g., ability) nor does it necessitate the removal of examinees who engage in rapid guessing. In addition, our method uniquely allows for the simultaneous modeling of a disengagement latent trait in addition to the trait of interest. The results indicate the model is quite useful for estimating individual differences among examinees in the disengagement latent trait and in providing more precise measurement of examinee ability relative to models ignoring rapid guesses or accommodating it in different ways. A simulation study reveals that our model results in less biased estimates of the trait of interest for individuals with rapid responses, regardless of sample size and rapid response rate in the sample. We conclude with a discussion of extensions of the model and directions for future research.