Notes and Quotes

Which Hypothesis to Choose?

"[Astronomer Johannes] Kepler's thought is, that of a number of variant hypotheses about the same facts, that one is true which shows why facts, which in the other hypotheses remain unrelated, are as they are, i.e., which demonstrates their orderly and rational mathematical connexion. To put it in his own summary: `Therefore, neither this nor that supposition is worthy of the name of an astronomical hypothesis, but rather that which is implied by both alike.' A true hypothesis is always a more inclusive conception, binding together facts which had hitherto been regarded as distinct; it reveals a mathematical order and harmony where before there had been unexplained diversity."

E.A. Burtt (1932) The Metaphysical Foundations of Modern Science. Reprinted 1954, Garden City NY: Doubleday Anchor. p.65. [Emphasis his].

The Practical Necessity of Units - Encore

"It is the vice or misfortune of thinkers about education to have chosen the methods of philosophy or of popular thought instead of those of science... Long after every statement about mental growth made in this book has been superseded by a truer one the method which it tries to illustrate will still be profitable and the ideals of accuracy and honesty in statistical procedure by which I hope it has been guided will still be honored. We conquer the facts of nature when we observe and experiment upon them. When we measure them we have made them our servants... The service rendered to physical science by the inch, the ounce, the ohm, the ampere, the calorie, etc., should be duplicated in mental science... Until we have such units all our investigations rest on insecure foundations."

Edward L. Thorndike (1903) Educational Psychology. New York: Lemcke and Buechner, pp.164-170.

Rasch's Outstanding Contribution

"Rasch (1960) has devised a truly new approach to psychometric problems... He makes use of none of the classical psychometrics, but rather applies algebra anew to a probabilistic model. The probability that a person will answer an item correctly is assumed to be the product of an ability parameter pertaining only to the person and a difficulty parameter pertaining only to the item. Beyond specifying one person as the standard of ability and one item as the standard of difficulty, the ability assigned to an individual is independent of that of other members of the group and of the particular items with which he is tested; similarly for the item difficulty... Indeed, these two properties were once suggested as criteria for absolute scaling (Loevinger 1947); at that time proposed schemes for absolute scaling had not been shown to satisfy the criteria, nor does Guttman scaling do so. Thus, Rasch must be credited with an outstanding contribution to one of the two central psychometric problems, the achievement of non-arbitrary measures. Rasch is concerned with a different and more rigorous kind of generalization than Cronbach, Rajaratnam, and Gleser. When his model fits, the results are independent of the sample of persons and of the particular items within some broad limits. Within these limits, generality is, one might say, complete."

Jane Loevinger (1965) in Person and population as psychometric concepts. Psychological Review, 72(2), 143-155.

Loevinger, J. 1947. A systematic approach to the construction and evaluation of tests of ability. Psychological Monographs, 61(4)

At MOMS, December 1997

"All the world is a cess-pool of raw data!"

Bonnie Roe

"But we have to live in the data!"

Ben Wright

"Happily, Rasch helps us clean up the mess."

John Michael Linacre

Quotes from different presentations at MOMS, Chicago, December 5, 1997


 To speak or not to speak    That is the question.

 Whether it is better
   to say out loud outrageous originalities
     so new, so simple and so decisive
       they dare the comfort of satisfied tradition,
         rend the gentle fabric of self-assured complacency
           strew into tatters the many cloaks
             of decency, tact, diplomacy?

 Or just, to rest mute and muffled,
   swallowing the unspoken,
     unspeakable words,
       harsh meal of indigestibles?
         and shrink into an ancient, ruined ball of dust!

Ben Wright (with apologies to William Shakespeare)
p. 101 in Ed Bouchard & Ben Wright, Kinesthetic Ventures. Chicago: MESA Press. 1997

Notes and Quotes … Rasch Measurement Transactions, 1997, 11:3 p. 579, 585.

Please help with Standard Dataset 4: Andrich Rating Scale Model

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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Coming Rasch-related Events
Sept. 15-16, 2017, Fri.-Sat. IOMC 2017: International Outcome Measurement Conference, Chicago,
Oct. 13 - Nov. 10, 2017, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps),
Oct. 25-27, 2017, Wed.-Fri. In-person workshop: Applying the Rasch Model hands-on introductory workshop, Melbourne, Australia (T. Bond, B&FSteps), Announcement
Jan. 5 - Feb. 2, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps),
Jan. 10-16, 2018, Wed.-Tues. In-person workshop: Advanced Course in Rasch Measurement Theory and the application of RUMM2030, Perth, Australia (D. Andrich), Announcement
Jan. 17-19, 2018, Wed.-Fri. Rasch Conference: Seventh International Conference on Probabilistic Models for Measurement, Matilda Bay Club, Perth, Australia, Website
April 13-17, 2018, Fri.-Tues. AERA, New York, NY,
May 25 - June 22, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps),
June 29 - July 27, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Further Topics (E. Smith, Winsteps),
Aug. 10 - Sept. 7, 2018, Fri.-Fri. On-line workshop: Many-Facet Rasch Measurement (E. Smith, Facets),
Oct. 12 - Nov. 9, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps),
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