Joint Modeling of Ability and Differential Speed Using Responses and Response Times (RR 16-04)

With computerized testing, it is possible to record both the responses of test takers to test questions (i.e., items) and the amount of time spent by a test taker in responding to each question. Various models have been proposed that take into account both test-taker ability and working speed, with many models assuming a constant working speed throughout the test. The constant working speed assumption may be inappropriate for various reasons. For instance, a test taker may need to adjust their pace due to time mismanagement, or a test taker who started out working too fast may reduce their working speed to improve their accuracy. A model is proposed here that allows for variable working speed. An illustration of the model using the Amsterdam Chess Test data is provided.