Item Analysis (Classical Test Theory)

Item analysis is the foundational psychometric procedure for evaluating the quality of individual test or scale items within the Classical Test Theory (CTT) framework, as systematised by Allen and Yen (1979) and Crocker and Algina (1986). It produces an item difficulty index, an item discrimination index, and a distractor analysis for each item, enabling test developers to identify items that are too easy, too hard, or failing to separate high- and low-ability respondents.