How Much Bias in answer till 3 wrong?

"Terminating the test after answering three consecutive items incorrectly is a common practice with individually-administered intelligence tests. Obviously, treating the not reached items as incorrect (which is the typical interpretation - that the examinee would not have answered any of the remaining items correctly) is not a good idea. This practice results in Rasch ability estimates that are biased. On the other hand, if you treat the data as missing, the bias is not as extreme, but it is still there."

Edward W. Wolfe, Michigan State University

Is this bias a serious problem? Ed Wolfe mentions further that he is doing authoritative simulation studies based on real data. But let's imagine a simple scenario. We have a uniform item bank of Rasch-behaving items. Start by administering an item three logits below the examinee. Then advance up the item bank, administering items equally spaced in difficulty. Stop after three consecutive failures. What examinee measures would we expect to obtain for different items spacings?

Effective of 3 consecutive errors rule

The Figure shows the results of a simple simulation study according to these criteria. Values close to -4 logits correspond to no correct answers at all. Although the overall bias is negligible, the impact on individual examinees can be huge! Definitely do not use the "3 error" stopping rule with a test containing closely spaced items!

How Much Bias? Wolfe, E.W., Linacre, J.M. … Rasch Measurement Transactions, 2000, 14:2 p.750

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
Oct. 6 - Nov. 3, 2023, Fri.-Fri. On-line workshop: Rasch Measurement - Core Topics (E. Smith, Facets),
Oct. 12, 2023, Thursday 5 to 7 pm Colombian timeOn-line workshop: Deconstruyendo el concepto de validez y Discusiones sobre estimaciones de confiabilidad SICAPSI (J. Escobar, C.Pardo)
June 12 - 14, 2024, Wed.-Fri. 1st Scandinavian Applied Measurement Conference, Kristianstad University, Kristianstad, Sweden
Aug. 9 - Sept. 6, 2024, Fri.-Fri. On-line workshop: Many-Facet Rasch Measurement (E. Smith, Facets),


The URL of this page is