Notes and Quotes

How Progress Happens!

That is the true test of a brilliant theory, says a member of the Nobel Economics Prize committee. What first is thought to be wrong is later shown to be obvious. People see the world as they are trained to see it, and resist contrary explanations. That's what makes innovation unwelcome and discovery almost impossible. An important scientific innovation rarely makes its way by gradually winning over and converting its opponents, noted the physicist Max Planck. What does happen is that its opponents gradually die out and that the growing generation is familiarized with the [new] idea from the beginning. No wonder that the most profound discoveries are often made by the young or the outsider, neither of whom has yet learned to ignore the obvious or live with the accepted wisdom.

From a New York Times Editorial, "Naked Orthodoxy", October 17, 1985

Once is Not Enough

Every astronomical instrument is made twice. First in the shop of the artisan who makes it as expertly as he can. Second in the astronomical observatory where the astronomer carefully works out its errors and, by meticulously allowing for them, makes the instrument into a more nearly perfect device than it had been when it left the artisan's hands.
Friedrich William Bessel (1784-1846) quoted in Isaac Asimov, "Eyes on the Universe" Boston: Houghton Mifflin, 1974. p.95.

So with Rasch measurement. First we design the best test that we can. Then we regulate its outcomes to construct the most useful result.

Friedrich Bessel detected apparent motion of 61 Cygni. By consensus of the astronomical community, Bessel got the credit for the first successful measurement of the distance to a star. Bessel's observational prowess, which had a strong theoretical dimension, was legendary. He developed the concept of the 'twice-built telescope.' Bessel knew that any telescope, even the extraordinary instruments coming out of Fraunhofer's shop, had flaws that would interfere with the kind of precision measurements necessary to detect parallax. So, he figured out a way to build a 'mental' model of the telescope that would expose its various idiosyncrasies. Knowledge of the mental model allowed the user to make allowances for the limitations of the telescope. Bessel would, for example, measure things that were known with great precision, record the telescope's configuration, and make a mental adjustment for the tiny, but known, errors thus observed. Bessel's 'twice-built telescope' gets the credit for the first parallax measurement. It was truly a major achievement capstoning more than two centuries of careful work on both the design and application of telescopes.
Karl Giberson's review of "Parallax: The Race to Measure the Cosmos. Alan W. Hirshfeld (New York, NY: W.H. Freeman and Company Publishers, 2001)" in Science & Theology News, December 2001

Measure-based Factor Analysis

Factor loading plot from principal component analysis of measures (not scores!) for 15 impairment group codes. Each point represents the calibrations for one group of 13 motor function items. Groups 1A, 1B, 1C and 2 relate to the brain. These contrast with group 4, spinal cord dysfunction, and group 5, amputation. The ends of the factors are labeled with the qualitative meanings of the differences in the item calibrations.

Heinemann AW, Linacre JM, Wright BD, Hamilton B, Granger CV (1994) Measurement characteristics of the Functional Independence Measure. Topics in Stroke Rehabilitation 1(3) p. 1-15.

The 1992 SIG Business Meeting

The SIG Business Meeting was held on April 22, 1992 as Session 32.45 of the AERA Meeting in San Francisco. Mary E. Lunz presided. The Meeting commenced with addresses by Richard Woodcock on "Rasch Technology and Test Engineering", and Jack Stenner on "Meaning and Method in Reading Comprehension Measurement".

Program Chair, Mary Lunz, report: There were 8 SIG Sessions at the 1992 AERA Meeting. The SIG accepted 90% of the proposals received. The names of the proposal reviewers were read in acknowledgement of their service to the SIG. SIG members were encouraged to start planning for the 1993 AERA Meeting in Atlanta, at which innovative session formats will be encouraged.

SIG Secretary/Treasurer, John M. Linacre, report: On 4/12/92 there were 308 SIG members, of whom 253 had already renewed for 1992-1993. Since many had renewed for multiple years, there were, in total, 750 renewed SIG-member-years. At AERA 1991, the SIG balance was $3,098.02. For 1991-1992, expenses were $2,534.41, income was $3,314.96, making the AERA 1992 balance $3,878.48. This is $5.17 per SIG-member-year. Production and mailing costs of Rasch Measurement to US-resident SIG members were $6.84 per year.

SIG Chair, David Andrich, was unable to attend, but, in a letter read by new Chair, Wim van der Linden, he thanked the membership for our support of the SIG and encouraged us to maintain an attitude of openness to new ideas, combined with realistic self-criticism.

Mary Lunz introduced the new elected SIG officers, Chair: Wim van der Linden, Secretary/Treasurer: Anne Fisher, and the appointed officers: Editor, Rasch Measurement, Editor: John Michael Linacre, Associate Editor: Ben Wright, Operations Manager: John Michael Linacre, Program Chair: Mary Lunz.

In his inaugural address, Wim van der Linden encouraged communication. Communication of the SIG's ideas to those outside. Communication by the SIG Officers to the SIG members, and especially communication by SIG members to the SIG Officers. In particular, he requested SIG members to correspond with him about issues that concern them.

In the business session that followed, George Engelhard Jr. invited participation in the seventh International Measurement Workshop (IOMW7), April 10-11, 1993 in Atlanta, just prior to AERA. Mark Wilson announced that Objective Measurement, Volume 1, was published. Volume 2 was about to be published, and Volume 3 would be co-edited by Mark Wilson and George Engelhard. Volume 3 will feature, but not be limited to, the IOMW7 program.

Notes and Quotes … Rasch Measurement Transactions, 1992, 6:1, passim

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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