Item Response Theory Study Pack

Understanding Item Response Theory (IRT)

Item Response Theory (IRT) is a statistical framework that analyzes the relationship between latent traits—unobservable characteristics such as abilities—and individual responses to assessment items. Unlike classical test theory, IRT emphasizes item-specific characteristics rather than relying primarily on total test scores.

Key Concepts

• Latent Trait: Refers to an unobservable attribute that influences performance, such as intelligence or skill level.
• Item Difficulty: This is a key factor within IRT, representing the probability of a correct response based on a respondent's latent trait and item characteristics.
• Response Function: A mathematical model that depicts how the probability of a correct response varies relative to the level of the latent trait.

IRT Models

IRT utilizes various models, each accounting for item difficulty and characteristics to enhance the precision of latent trait measurements. Understanding these models improves the practical applications of IRT in educational contexts.