Background: As Japanese nursing colleges increasingly require common criteria for assessing practical nursing ability prior to entering clinical hospital practice, it is important to construct a test item bank that can facilitate the evaluation of multiple domains. However, ordinal IRT models, such as the 2 parameter logistic model (2PL), operate under the assumption of unidimensionality, preventing application to comprehensive testing of multiple domains. Method: We conducted a computer-based test with items from 20 domains, classified into three areas: (1) basic medicine, (2) basic nursing, and (3) clinical nursing. About 780 students answered items, which were applied to common-item design and calibrated item parameters using two strategies; the first strategy assumed one-factor model for each area, the second strategy assumed unidimensionality by domain. Conclusion: For constructing an item bank, estimating item parameters by domain results in larger test information and more appropriate parameter estimates than estimating parameters by area.
