Item Response Theory

Synonyms

Modern test theory

Definition

Item response theory (IRT), sometimes referred to as modern test theory, is a branch of psychometrics which seeks to understand and statistically model how a person will respond given a certain level of an underlying characteristic (e.g., cognitive ability, depression, etc.) and the properties of a questionnaire, test, or survey item. First developed in the 1950s and 1960s, and increasing in popularity from the 1970s onwards, IRT is a set of analytic tools with a broad range of applications in the field of personality and individual differences.

Introduction

In individual differences research, attributes such as “intelligence,” “neuroticism,” or “well-being” are commonly conceptualized as latent attributes that cannot be directly observed but whose levels can be gauged using sets of questionnaire-type items. Item response theory provides a framework for linking latent attribute levels to observed questionnaire responses in a mathematically precise...