Rasch Invents Weight and "Ounces"

One might wonder how civilization ever arrived at the efficient and reliable abstraction we call "weight" -- measured out, for instance, in ounces? We could not get along without this lovely abstraction. Not only physics and engineering, but also commerce would collapse. But where did the measurement of weight come from? How did it develop?

We cannot trace its full history, because most of it was never recorded. But we can reenact, right now, an experiment which shows the irresistible connection between the simplest possible comparisons and measured weight. Merely compare two objects for their heft by holding one in each hand. Record which one feels heavier. Nothing more. A psychometric construction, built from a set of these simplest of all observations, produces a linear equivalent to "objective" weight.

Ellie Choi poured different amounts of rice into 10 paper cups, sealed the cups, and labeled them "A" through "J" in random order. Then she asked each of 13 students she encountered to take pairs of cups, one in each hand, and tell her which cup felt heavier. 10 cups produce 45 pairings per student. Her experiment produced 580 independent paired comparisons with the heavier-feeling cup scored "1", each time, and the lighter-feeling cup scored "0". After Ellie had collected these data, she weighed each cup on a postal meter to determine its "official" weight in ounces.

When the simple dichotomous paired comparisons were analyzed using Facets, Ellie found that the Rasch calibrations of the 10 cups formed a statistically linear relation with their weight in ounces. Her picture of this relationship is shown.

The implications of Ellie's experiment for the history of measurement is that the linear abstraction of "weight" was resident in our simplest comparison judgements from the beginning. All we had to do over the centuries was to find out, step-by-step, how to make the implications of our simplest comparisons into objective and reproducible measures.

Choi, Sungeon "Ellie" (1995) Using Paired Comparisons to Determine Weight Perception. Unpublished paper. University of Chicago.

Rasch Invents "Ounces". Choi S. E. … Rasch Measurement Transactions, 1997, 11:2 p. 557.

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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