Rasch: Too Complicated or Too Simple?

A colleague writes:

"I've proposed a Rasch analysis, not a Classical analysis, but people here are not familiar with it and they are not very open to other perspectives than Classical Test Theory (CTT). I've try to explain to them all the advantages of Rasch, but they said: "This is to complicated and people won't understand it. We need a Classical Analysis." But on another project, people were very critical about Rasch and proposed instead a 3-PL model."

Comment: Yes, familiar methods are difficult to unseat. The astrolabe was still being used 150 years after Isaac Newton demonstrated better methods of locating the planets. Classical methods usually survive until a situation arises they can't deal with, such as missing data, adaptive tests, maintaining criterion-based pass-fail points, test-equating with small samples ...

Advocating the 3-PL model means that they expect their students to guess answers at random - so that the student measures will have a chaotic component, lowering the predictive validity of the test. They also expect their items to differ widely in discrimination - which means they expect their item writers to write deficient items, lowering the construct validity of the test.

The 3-P logistic model was designed to model messy data. According to Martha Stocking, an advocate of 3-PL, "Building statistical models is just like this. You take a real situation with real data, messy as this is, and build a model that works to explain the behavior of real data." New York Times, 2-10-2000.

Instead of designing a descriptive model, such as 3-PL, to explain messy data, Georg Rasch designed a model that demands useful data and points out where the data is messy. Messy data produces messy findings. Useful data produces useful findings. But most statisticians believe that the data, however messy, always tells the truth. The problem is that the messy data's "truth" may not be the truth that we need for decision-making.

Rasch: Too Complicated or Too Simple?, … Rasch Measurement Transactions, 2006, 20:3 p. 1065

Rasch Books and Publications
Invariant Measurement: Using Rasch Models in the Social, Behavioral, and Health Sciences, 2nd Edn. George Engelhard, Jr. & Jue Wang	Applying the Rasch Model (Winsteps, Facets) 4th Ed., Bond, Yan, Heene	Advances in Rasch Analyses in the Human Sciences (Winsteps, Facets) 1st Ed., Boone, Staver	Advances in Applications of Rasch Measurement in Science Education, X. Liu & W. J. Boone	Rasch Analysis in the Human Sciences (Winsteps) Boone, Staver, Yale
Introduction to Many-Facet Rasch Measurement (Facets), Thomas Eckes	Statistical Analyses for Language Testers (Facets), Rita Green	Invariant Measurement with Raters and Rating Scales: Rasch Models for Rater-Mediated Assessments (Facets), George Engelhard, Jr. & Stefanie Wind	Aplicação do Modelo de Rasch (Português), de Bond, Trevor G., Fox, Christine M	Appliquer le modèle de Rasch: Défis et pistes de solution (Winsteps) E. Dionne, S. Béland
Exploring Rating Scale Functioning for Survey Research (R, Facets), Stefanie Wind	Rasch Measurement: Applications, Khine	Winsteps Tutorials - free Facets Tutorials - free	Many-Facet Rasch Measurement (Facets) - free, J.M. Linacre	Fairness, Justice and Language Assessment (Winsteps, Facets), McNamara, Knoch, Fan
Other Rasch-Related Resources: Rasch Measurement YouTube Channel
Rasch Measurement Transactions & Rasch Measurement research papers - free	An Introduction to the Rasch Model with Examples in R (eRm, etc.), Debelak, Strobl, Zeigenfuse	Rasch Measurement Theory Analysis in R, Wind, Hua	Applying the Rasch Model in Social Sciences Using R, Lamprianou	El modelo métrico de Rasch: Fundamentación, implementación e interpretación de la medida en ciencias sociales (Spanish Edition), Manuel González-Montesinos M.
Rasch Models: Foundations, Recent Developments, and Applications, Fischer & Molenaar	Probabilistic Models for Some Intelligence and Attainment Tests, Georg Rasch	Rasch Models for Measurement, David Andrich	Constructing Measures, Mark Wilson	Best Test Design - free, Wright & Stone Rating Scale Analysis - free, Wright & Masters
Virtual Standard Setting: Setting Cut Scores, Charalambos Kollias	Diseño de Mejores Pruebas - free, Spanish Best Test Design	A Course in Rasch Measurement Theory, Andrich, Marais	Rasch Models in Health, Christensen, Kreiner, Mesba	Multivariate and Mixture Distribution Rasch Models, von Davier, Carstensen

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