A Psychometric Model for Discrete-Option Multiple-Choice Items

Discrete-option multiple-choice (DOMC) items differ from traditional multiple-choice (MC) items in the sequential administration of response options (up to display of the correct option). DOMC can be appealing in computer-based test administrations due to its protection of item security and its potential to reduce testwiseness effects. A psychometric model for DOMC items that attends to the random positioning of key location across different administrations of the same item is proposed, a feature that has been shown to affect DOMC item difficulty. Using two empirical data sets having items administered in both DOMC and MC formats, the variability in key location effects across both items and persons is considered. The proposed model exploits the capacity of the DOMC format to isolate both (a) distinct sources of item difficulty (i.e., related to the identification of keyed responses versus the ruling out of distractor options) and (b) distinct person proficiencies related to the same two components. Practical implications in terms of the randomized process applied to schedule item key location in DOMC test administrations are considered.