Item Response Theory

Item response theory, also called latent trait theory or modern mental test theory, is a psychometric paradigm for designing, analyzing and scoring tests, questionnaires and similar instruments that measure ability, attitude or other traits. It models the relationship between a test taker's performance on a single item and that test taker's overall level on the ability the item is meant to measure, characterizing each item by its own difficulty, discrimination and guessing parameters rather than assuming, as simpler scaling methods do, that every item is an equally difficult, interchangeable replica of the others. Because it can handle more complicated testing situations than the older classical test theory, item response theory is the preferred method behind several high stakes assessments, including the Graduate Record Examination and the Graduate Management Admission Test.