The Rasch Model and the Quest for Perfection

"The Rasch model is too rigid." "It demands too much from our data." "It throws out too many items." Perhaps the Rasch model is a mathematical Maud:

Perfectly beautiful: let it be granted her:
where is the fault?
Faultily faultless, icily regular, splendidly null.
Dead perfection, no more.
Tennyson

Are Rasch analysts wrong to seek perfection? The book, "The Customer is the Key" (M.M. Lee with J.N. Sheth, Wiley, 1991) describes the six characteristics of businesses identified as "winners". They are summarized thus:

Fig. 1. Six key characteristics of "winning" businesses. (redrawn from Fig. 3.1, Lele & Sheth, 1991).

Notice the extreme language, "impossible", "obsessive", "everyone", "maximize." Surely no business can actually achieve these characteristics? Lele & Sheth admit that they can't, but "these companies realize that performance often falls short of expectations. Therefore, in order to deliver merely good results, they must set their sights on impossible goals. .... knowing that they are likely to achieve something less than what they aim for is the most compelling reason that they can give for aiming for the best" (p. 61). This suggests that Fig. 1 also applies to "winning" measurement projects, see Fig.2:

Fig. 2. Six key characteristics of "winning" measurement projects. (after Lele & Sheth, 1991).

"Science must begin with myths." (Alexander Pope)

"Yours is a distinctive vision, you believe. And it's also ideal. After all, you want to set a new standard of perfection, beauty or excellence. You want to be a model for others. Yours is an ideal and unique image of the future" (J.M Kouzes & B.Z. Posner, The Leadership Challenge, Jossey-Bass, 1995, p. 96)

Let our myth be that perfection is attainable, and let us resist the shame of having mediocrity thrust upon us (Joseph Heller, Catch-22).

John Michael Linacre

Rasch model and the quest for perfection, Lee M, Sheth J, Linacre J … Rasch Measurement Transactions, 2004, 18:3 p. 985

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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