Rasch model - Wikipedia, the free encyclopedia

Rasch model

Rasch models are used for analysing data from assessments to measure things such as abilities, attitudes, and personality traits. For example, they may be used to estimate a student's reading ability from answers to questions on a reading assessment, or the extremity of a person's attitude to capital punishment from responses on a questionnaire.

 

Rasch models are particularly used in psychometrics, the field concerned with the theory and technique of psychological and educational measurement. In addition, they are increasingly being used in other areas, including the health profession and market research because of their general applicability.

Scaling

Interpreting scale locations

Features of the Rasch model

Other considerations

A criticism of the Rasch model is that it is overly restrictive or prescriptive because it does not permit each item to have a different discrimination. A criticism specific to the use of multiple choice items in educational assessment is that there is no provision in the model for guessing because the left asymptote always approaches a zero probability in the Rasch model.

Baker, F. (2001). The Basics of Item Response Theory. ERIC Clearinghouse on Assessment and Evaluation, University of Maryland, College Park, MD. Available free with software included from IRT at Edres.org

Wu, M. & Adams, R. (2007). Applying the Rasch model to psycho-social measurement: A practical approach. Melbourne, Australia: Educational Measurement Solutions. Available free from Educational Measurement Solutions