Psychometrics

Psychometrics refers to the measurement of abilities, traits, and attitudes with questionnaires and tests. While such techniques as factor analysis and structural equation modeling can be thought to fall under the umbrella of psychometrics, this article focuses on item response theory (IRT), which studies the relationship between traits of individuals and their responses to items on a test. Although the roots of IRT are in educational testing, it has applications in many other disciplines. Much of the pioneering work in the field is attributed to Frederick Lord.

The trait studied in IRT is most often a latent trait, one that cannot be measured directly. IRT describes how a person's observable behavior, or his or her performance on a test, is related to this latent trait or ...