Item response theory
Definition
“In psychometrics, item response theory (IRT: also known as latent trait theory, strong true score theory, or modern mental test theory) is a body of theory describing the application of mathematical models to data from questionnaires and tests as a basis for measuring abilities, attitudes, or other variables. It is used for statistical analysis and development of assessments, often for high stakes tests such as the Graduate Record Examination. At its most basic level, it is based on the idea that the probability of getting an item correct is a function of a latent trait or ability. For example, a person with higher intelligence would be more likely to correctly respond to a given item on an intelligence test.” (Item response theory (Wikipedia, retrieved 14:58, 9 March 2009 (UTC)).
“In many educational and psychological measurement situations, there is an underlying variable of interest. This variable is often something that is intuitively understood, such as "intelligence". [...] In academic areas, one can use descriptive terms such as reading ability and arithmetic ability. Each of these is what psychometricians refer to as an unobservable, or latent, trait.[...] A primary goal of educational and psychological measurement is the determination of how much of such a latent trait a person possesses.” [http://echo.edres.org:8080/irt/baker/chapter1.pdf Baker, 2001:5).
See also: Methodology tutorial - descriptive statistics and scales
Links
- Item response theory (Wikipedia).
Bibliography
- Baker, Frank (2001). The Basics of Item Response Theory. ERIC Clearinghouse on Assessment and Evaluation, University of Maryland, College Park, MD. The first edition is available as free on line book (chapters available as PDF)