Notes and Quotes

All Measuring the Same Thing

Luigi Tesio (2003, Measuring Behaviours and Perceptions: Rasch Analysis as a Tool for Rehabilitation Research, Journal of Rehabilitation Medicine, 2003; 35: 105-115) presents a remarkable summary of the progress made in the last 15 years. His Table III (reproduced here) supports the contention that instruments developed at different times for different purposes may actually measuring the same thing. Historically, this parallels a major development in thermometry.

Source scale Item Logit measure (0-100 transform) Fit mean-square
Low sit
(raising from)
Personal care
0. 71
1. 13
0. 93
1. 07
1. 30
0. 79
0. 92
0. 83
0. 86

Table III. Rasch measure (logit transformed into 0-100 units) and fit mean square of the BACKILL scale for low-back pain syndromes, derived from existing scales (14). McGILL:McGill Pain Questionnaire-short form; OSWESTRY: Oswestry Low Back Pain Disability Questionnaire; FASQ: Functional Assessment Screening Questionnaire. Items made up a linear measure of "back illness". Fit indexes revealed good fit to the Rasch model.

"The development of common constructs can also contribute to a cohesive knowledge core and further enhance theoretical understanding."
Michael J. Feuer, Lisa Towne, and Richard J. Shavelson, in "Scientific Culture and Educational Research," Educational Researcher, 2002, 31, 8, p. 11

"... for only by varied iteration can alien conceptions be forced on reluctant minds."
Herbert Spencer, in the preface to The Data of Ethics, 1881. Courtesy of Lise DeShea

The Spirit of the Age and Fashion
in Data Analysis Methods

"What today is a state-of-the-art research approach is tomorrow already like yesterday's snow."
Then, 1980?Now, 2000:
Categorical data
Statistical significance
Metrical data
Effect size
Jü Rost. (2002) Zeitgeist und Moden empirischer Analysemethoden.
ZUMA - Nachrichten Spezial Band 8, Von Generation zu Generation.

Psychometrics is at a Crossroads

I've come to believe that Psychometrics has become

1. too inbred - too many of us are paying attention only to ourselves. We have forgotten our users - psychologists and other social scientists.

2. too driven by mathematics without regard to practical usefulness.

3. too focused on minutiae - often mathematically tweaking existing work to provide a minute new feature that makes little (if any) useful difference.

4. to focused on methods and models that have gotten way more complicated than users can understand - and than we can communicate to anyone other than ourselves.

5. insufficiently driven by its original purpose of trying to provide mathematical tools useful to Psychologists.

The common denominator of these points is:

we are too focused on mathematics at the expense of usefulness.

I believe that Psychometrics is in need of rejuvenation, and that this can be done by expanding the purview of Psychometrics by working on

1. the development and use of Psychological tools that are useful in strengthening the scientific basis of the practice of Statistics; while at the same time strengthening the traditional focus on

2. the development and use of Statistical tools useful in strengthening the scientific basis of the practice of Psychology.

I encourage the field of Psychometrics to encompass and encourage the use of Psychological tools that are useful in strengthening the scientific basis of the practice of Statistics. These tools include the theories and methods of cognitive and perceptual Psychology, which are already being used to improve the scientific basis of the practice of Statistics - especially for Graphics and Software design.

Excerpted and edited from: Forrest W. Young, L.L. Thurstone Psychometric Laboratory, University of North Carolina, (1996) New Directions in Psychometrics. Invited presentation at the annual meeting of the Psychometric Society, Banff, Canada

Notes and Quotes … Rasch Measurement Transactions, 2003, 17:1, 916ff.

Rasch Publications
Rasch Measurement Transactions (free, online) Rasch Measurement research papers (free, online) Probabilistic Models for Some Intelligence and Attainment Tests, Georg Rasch Applying the Rasch Model 3rd. Ed., Bond & Fox Best Test Design, Wright & Stone
Rating Scale Analysis, Wright & Masters Introduction to Rasch Measurement, E. Smith & R. Smith Introduction to Many-Facet Rasch Measurement, Thomas Eckes Invariant Measurement: Using Rasch Models in the Social, Behavioral, and Health Sciences, George Engelhard, Jr. Statistical Analyses for Language Testers, Rita Green
Rasch Models: Foundations, Recent Developments, and Applications, Fischer & Molenaar Journal of Applied Measurement Rasch models for measurement, David Andrich Constructing Measures, Mark Wilson Rasch Analysis in the Human Sciences, Boone, Stave, Yale
in Spanish: Análisis de Rasch para todos, Agustín Tristán Mediciones, Posicionamientos y Diagnósticos Competitivos, Juan Ramón Oreja Rodríguez

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