The Rasch model, named after Georg Rasch, is a psychometric model for analyzing categorical data, such as answers to questions on a reading assessment or questionnaire responses, as a function of the trade-off between the respondent's abilities, attitudes, or personality traits, and the item difficulty.[1][2] For example, they may be used to estimate a student's reading ability or the extremity of a person's attitude to capital punishment from responses on a questionnaire. In addition to psychometrics and educational research, the Rasch model and its extensions are used in other areas, including the health profession,[3]agriculture,[4] and market research.[5][6]
The mathematical theory underlying Rasch models is a special case of item response theory. However, there are important differences in the interpretation of the model parameters and its philosophical implications[7] that separate proponents of the Rasch model from the item response modeling tradition. A central aspect of this divide relates to the role of specific objectivity,[8] a defining property of the Rasch model according to Georg Rasch, as a requirement for successful measurement.
^Rasch, G. (1980) [1960]. Probabilistic models for some intelligence and attainment tests. Foreword and afterword by B.D. Wright (Expanded ed.). Chicago: The University of Chicago Press.
^Bechtel, Gordon G. (1985). "Generalizing the Rasch Model for Consumer Rating Scales". Marketing Science. 4 (1). Institute for Operations Research and the Management Sciences (INFORMS): 62–73. doi:10.1287/mksc.4.1.62. ISSN0732-2399.
^Wright, B. D. (1977). Solving measurement problems with the Rasch model. Journal of Educational Measurement, 14(2), 97-116.
^Linacre J.M. (2005). Rasch dichotomous model vs. One-parameter Logistic Model. Rasch Measurement Transactions, 19:3, 1032
^Rasch, G. (1977). On Specific Objectivity: An attempt at formalizing the request for generality and validity of scientific statements. The Danish Yearbook of Philosophy, 14, 58-93.