A simulation study to the dually adaptive online IRT testing system

The item response theory (IRT) gives us valuable information about the difficulties of items as well as the abilities of examinees. Adaptive testing using the IRT provides the most appropriate items to examinees automatically. However, the item parameters remain the same even if the features of the examinees and the number of examinees change. We propose to use the dually adaptive online IRT testing system, where “dually adaptive” means that one is targeted to the adequate item selection and the other is to the adjustment of the difficulty values for items. The key idea for this is to use the matrix completion method to the incomplete matrix. By using the simulation study, we found that the proposed method works well.