"Has it helped us understand better what kids know?" I believe the answer to these questions is not "no" but a resounding "yes." Unfortunately, many test developers using IRT do not take advantage of the powerful interpretation features that become accessible when person abilities and item difficulties have been calibrated on a common Rasch scale. This is probably one reason that some observers have not appreciated some benefits of Rasch measurement.
Allow me to take a recent chapter I have written, and elaborate on its contents for those who may be interested:
Woodcock, R. W. (1999). What can Rasch-based scores convey about a person's test performance? In S. E. Embretson & S. L. Hershberger (Eds.), The new rules of measurement: What every psychologist and educator should know. Hillsdale, NJ: Lawrence Erlbaum Assoc.
The title of the chapter explains its purpose and why it is relevant to this topic. The chapter begins by describing four levels of information that are potentially available from any test and how the use of Rasch measurement helps exploit this available information. The chapter describes several procedures that facilitate interpretation of test performance including:
1) Rasch-scaled item maps.
2) The "Relative Proficiency Index" which states a prediction of the subject's level of success on tasks performed with 90% success by average age- or grade-mates. This index is similar to the Snellen Index used in vision examinations. An example is "67/90" which states that the subject is predicted to perform with 67% success those tasks that others perform with 90% success.
3) The "Developmental Zone" used in cognitive tests and the "Achievement Zone" used in achievement tests. These zones identify a range along an age or grade scale from the level at which the subject will find tasks "easy" (RPI = 96/90) to the level at which the subject will find tasks "difficult" (RPI = 75/90).
4) After some other examples, the chapter concludes with an example test report based on an assessment of Spanish and English language proficiency in a bilingual student. The scores and text highlighted by bold type in a figure in the chapter identify the information derived from Rasch-based scales that could not have been provided by traditional CTT procedures. Half of the information in the report, and probably the most important information for teachers and others concerned with the question of what this child knows and can do, appears in bold.
The Embretson & Hershberger book has a lot of good information and I recommend it to you.
Richard W. Woodcock
Has Rasch scaling made better tests? Woodcock R.W. Rasch Measurement Transactions, 2000, 14:1 p.738
|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|
|Forum||Rasch Measurement Forum to discuss any Rasch-related topic|
Go to Top of Page
Go to index of all Rasch Measurement Transactions
AERA members: Join the Rasch Measurement SIG and receive the printed version of RMT
Some back issues of RMT are available as bound volumes
Subscribe to Journal of Applied Measurement
Go to Institute for Objective Measurement Home Page. The Rasch Measurement SIG (AERA) thanks the Institute for Objective Measurement for inviting the publication of Rasch Measurement Transactions on the Institute's website, www.rasch.org.
|Coming Rasch-related Events|
|Apr. 14-17, 2020, Tue.-Fri.||International Objective Measurement Workshop (IOMW), University of California, Berkeley, https://www.iomw.org/|
|May 22 - June 19, 2020, Fri.-Fri.||On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com|
|June 26 - July 24, 2020, Fri.-Fri.||On-line workshop: Practical Rasch Measurement - Further Topics (E. Smith, Winsteps), www.statistics.com|
|June 29 - July 1, 2020, Mon.-Wed.||Measurement at the Crossroads 2020, Milan, Italy , https://convegni.unicatt.it/mac-home|
|July - November, 2020||On-line course: An Introduction to Rasch Measurement Theory and RUMM2030Plus (Andrich & Marais), http://www.education.uwa.edu.au/ppl/courses|
|July 1 - July 3, 2020, Wed.-Fri.||International Measurement Confederation (IMEKO) Joint Symposium, Warsaw, Poland, http://www.imeko-warsaw-2020.org/|
|Aug. 7 - Sept. 4, 2020, Fri.-Fri.||On-line workshop: Many-Facet Rasch Measurement (E. Smith, Facets), www.statistics.com|
|Oct. 9 - Nov. 6, 2020, Fri.-Fri.||On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com|
|June 25 - July 23, 2021, Fri.-Fri.||On-line workshop: Practical Rasch Measurement - Further Topics (E. Smith, Winsteps), www.statistics.com|
The URL of this page is www.rasch.org/rmt/rmt141j.htm