Chicago Objective Measurement Table

COMET, a monthly meeting of objective measurement specialists, began in November, 1993 on the University of Chicago campus. In Spring 1997, it moved downtown to the Rehabilitation Institute of Chicago. COMET participants
• present preliminary results from projects,
• describe unusual applications of measurement,
• introduce innovations in reporting results,
• seek advice on specific measurement problems, and
• try out presentations planned for other audiences.

The meetings are usually held on the third of the month Thursday and start at 4:00 P.M. They are open to everyone without fees or registration. After the planned program, COMET typically moves to a neighborhood restaurant for dinner. To attend COMET or present a paper, contact Rita Bode

1997-1998 Meeting Summary

Several meetings addressed the issue of equating instruments measuring physical functioning. Richard Smith (RFI/Marianjoy Rehabilitation Institute) discussed the consolidation of the MOS SF36 and the LSU HSI Physical Functioning Scales. Michael Linacre (MESA), Rita Bode and Allen Heinemann (both from Rehabilitation Institute of Chicago) showed the influence that category structure in rating scales has on item difficulty estimates. Rita Bode presented an example from the SF36, demonstrating the benefits of aligning rating scale structures using "pivot anchoring" to establish meaningful item difficulties.

Donna Tatum (Meaningful Measurement) described development of a Competency Map: An item bank for speech evaluation for public speaking that crosses eight public speaking content domains (credibility, vocal, nonverbal, language, topic/structure, evidence/support, audience, and motivated sequence), yet is encompassed by one measurement framework.

Tom O'Neill (American Society of Clinical Pathologists) presented his study of item security when the item selection algorithm in a computerized adaptive test is allowed to present examinees with questions already presented in a previous CAT administration. His results show item security is not breached when some previously seen questions are administered to some repeating examinees.

In a Comparison of performance on written and oral examinations, Mary Lunz (American Society of Clinical Pathologists) reported the relationship between written and oral performance on a certification examination in a medical specialty. Some candidates who did very well on the written examination were unable to demonstrate adequate clinical skills on the oral. There was also substantial variation among candidates who performed moderately well on both examinations. Since these examinations are designed to test different skills, these results were reassuring.

Matthew Schulz (American College Testing) presented Performance of optimal tests for Pass/Fail decisions addressing the consistency and accuracy of classification in the presence of off-target items in multiple-choice tests. These items introduce noise, so reducing classification accuracy. For examinees with low-borderline ability on a test he investigated, maximum accuracy and reliability could be attained with as few as four out of the thirty test items.

In Predicting College Football Point Spreads, Patrick B. Fisher (Rehabilitation Institute of Chicago) presented empirical results showing the increased precision that Rasch analysis gives him in predicting NCAA football point spreads. COMET participants suggested many further refinements, and also uses for these results.

Nikolaus Bezruczko

Schedule for Fall 1998 - Winter 1999 COMET Meetings
September 17Betty BergstromTesting on the Internet
October 29Chih-Hung ChangQOL item banking and CAT
November 19Mary LunzFacets and Oral Examinations
December 17Richard SmithEquating polytomous scales
January 21Winnie LopezUnderstanding midpoint responses
February 18Mark StoneItem/person validity
March 18Greg Stone & Jeff MosenkisValidating content by traditional and paired approaches

Bezruczko N. (1998) Chicago Objective Measurement Table. Rasch Measurement Transactions 12:1 p. 620.

Chicago Objective Measurement Table. Bezruczko N. … Rasch Measurement Transactions, 1998, 12:1 p. 620.

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
Oct. 6 - Nov. 3, 2023, Fri.-Fri. On-line workshop: Rasch Measurement - Core Topics (E. Smith, Facets),
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