Optimal Reassembly of Shadow Tests in CAT.

Even in the age of abundant and fast computing resources, concurrency requirements for large-scale online testing programs still put an uninterrupted delivery of computer-adaptive tests at risk. In this study, to increase the concurrency for operational programs that use the shadow-test approach to adaptive testing, we explored various strategies aiming for reducing the number of reassembled shadow tests without compromising the measurement quality. Strategies requiring fixed intervals between reassemblies, a certain minimal change in the interim ability estimate since the last assembly before triggering a reassembly, and a hybrid of the two strategies yielded substantial reductions in the number of reassemblies without degradation in the measurement accuracy. The strategies effectively prevented unnecessary reassemblies due to adapting to the noise in the early test stages. They also highlighted the practicality of the shadow-test approach by minimizing the computational load involved in its use of mixed-integer programming.