IRT and Confusion about Rasch Measurement

The International Journal of Educational and Psychological Assessment contains papers relating to Classical Test Theory (CTT), Item Response Theory (IRT) and Rasch measurement. Unfortunately these papers present a confusing perspective on Rasch measurement. For instance,

1. Cutoff Scores: The Basic Angoff Method and the Item Response Theory Method. Niclie Tiratira.

This articles employs Bigsteps and Winsteps, without citing the sources, in an IRT context, and reports results with no sense of the fingernails-on-the-blackboard dissonance infit and outfit have relative to IRT.

2. The Measurement of Change in Groups and Individuals With Particular Reference to the Value of Change Scores: A New IRT-Based Methodology for the Assessment of Treatment Effects. Jörg A. Prieler and John Raven.

This article asks and answers the following questions:

Question 1. Does the portrayal of parallel item characteristic curves (ICCs) in Rasch computer analysis output mislead many into thinking the item difficulty order is independent of ability?
Their answer: Yes. But the Rasch answer: No. Rasch analysis deliberately constructs item difficulties which are as independent as statistically possible of ability.

Question 2. Do the crossing ICCs in a 3-parameter IRT analysis indicate that the appropriate model for these data is one that describes the interactions making item and person estimates dependent on one another?
Their answer: Yes. But the Rasch answer: No. Crossing ICCs are never an appropriate model (except for some polytomous models.) Construct validity demands that the item difficulty hierarchy is invariant across person abilities.

Question 3: Are the "most popular versions of Item Response Theory" often loosely referred to as "the Rasch model"?
Their answer: Yes. But the Rasch answer: No. IRT is a descriptive statistical methodology originated by Frederic Lord. Rasch analysis is a prescriptive measurement methodology originated by Georg Rasch. One of Lord's IRT models resembles a Rasch model.

Comment: What chaos! The force of the academically-dominant IRT paradigm's influence is truly impressive: it is able to make people see things that don't exist, and to let them ignore existing things that don't fit with their preconceptions. How will these kinds of misconceptions ever be corrected? Will it all come out in the wash at some point down the road when invariance, sufficiency and additivity are demanded as basic elements of credible psychometric measurement?

William P. Fisher, Jr.

IRT and Confusion about Rasch Measurement, W.P. Fisher, Jr. ... Rasch Measurement Transactions, 2010, 24:2 p. 1288

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

To be emailed about new material on
please enter your email address here:

I want to Subscribe: & click below
I want to Unsubscribe: & click below

Please set your SPAM filter to accept emails from welcomes your comments:

Your email address (if you want us to reply):


ForumRasch 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,

Coming Rasch-related Events
July 31 - Aug. 3, 2017, Mon.-Thurs. Joint IMEKO TC1-TC7-TC13 Symposium 2017: Measurement Science challenges in Natural and Social Sciences, Rio de Janeiro, Brazil,
Aug. 7-9, 2017, Mon-Wed. In-person workshop and research coloquium: Effect size of family and school indexes in writing competence using TERCE data (C. Pardo, A. Atorressi, Winsteps), Bariloche Argentina. Carlos Pardo, Universidad Catòlica de Colombia
Aug. 7-9, 2017, Mon-Wed. PROMS 2017: Pacific Rim Objective Measurement Symposium, Sabah, Borneo, Malaysia,
Aug. 10, 2017, Thurs. In-person Winsteps Training Workshop (M. Linacre, Winsteps), Sydney, Australia.
Aug. 11 - Sept. 8, 2017, Fri.-Fri. On-line workshop: Many-Facet Rasch Measurement (E. Smith, Facets),
Aug. 18-21, 2017, Fri.-Mon. IACAT 2017: International Association for Computerized Adaptive Testing, Niigata, Japan,
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),
The HTML to add "Coming Rasch-related Events" to your webpage is:
<script type="text/javascript" src=""></script>


The URL of this page is