Medieval Measurers

Definition of Objective Measurement

Objective measurement is the repetition of a unit amount that maintains its size, within an allowable range of error, no matter which instrument, intended to measure the variable of interest, is used and no matter who or what relevant person or thing is measured.

An objective measurement estimate of amount stays constant and unchanging (within the allowable error) across the persons measured, across different brands of instruments, and across instrument users. The goal of objective measurement is to produce a reference standard common currency for the exchange of quantitative value, so that all research and practice relevant to a particular variable can be conducted in uniform terms. Objective measurement research tests the extent to which a given number can be interpreted as indicating the same amount of the thing measured, across persons measured, and brands of instrument.

Our intuitions about measurement are confirmed with everyday trips to the grocery store. For instance, when selecting apples from a bin, one may readily see that three large apples might contain twice as much edible fruit as three small ones. To account for this difference, the cost is not proportionate with the actual, concrete number of apples, but with their abstract weight.

Most measurement efforts in the human sciences tally differently sized test or survey answers and stop there, mistakenly treating these concrete counts as abstract measures of amount. Over 70 years of objective measurement research and practice have established conclusively 1) the viability of scaling different instruments intended to measure a common variable onto a single reference standard ruler, and 2) the value of developing objective measurement-based construct theories.

The extent to which the unit amount remains constant within a particular range of error cannot be assumed. Research in objective measurement is largely a matter of asserting and testing hypotheses concerning the quantitative status of psychosocial variables. Such research might begin from an instrument, data, a theory, or some combination of these, but proceeds in a manner that uses each of these to check and improve the other two.

Objective measurement can be achieved and maintained employing a wide variety of approaches and methods. These include testing for concatenation, conjoint additivity, Guttman ordering, infinite divisibility, parameter separation or sufficiency. Objective measurement operates within the research traditions of fundamental measurement theory, item response theory, and latent trait theory.

Written by the Program Committee of the Institute for Objective Measurement. December 2000.

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 Journal of Applied Measurement
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
Rasch Books and Publications: Winsteps and Facets
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 Appliquer le modèle de Rasch: Défis et pistes de solution (Winsteps) E. Dionne, S. Béland
Introduction to Many-Facet Rasch Measurement (Facets), Thomas Eckes Rasch Models for Solving Measurement Problems (Facets), George Engelhard, Jr. & Jue Wang 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
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

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