Diagnosis menu

The Diagnosis pull-down menu suggests a step-by-step procedure for investigating the results of your analysis.


Click on the Table name to go to the Table description:



A. Item Polarity: check that all items are aligned in the same direction on the latent variable, same as Table 26. Check that all items have positive correlations. Use IREFER= and IVALUE= to point all items in the same direction, or KEY1= to correct a multiple-choice key error. IDFILE= to delete (for the moment) uncooperative items.


B. Empirical Item-Category Measures: check that all categories for all items are aligned in the same direction, same as Table 2.6. For multiple-choice items, see Table 2 for MCQ. Check that correct answers, and higher category values corresponding to "more" of the variable, are to the right.


C. Category Function: check that all categorization functioned as intended, same as Table 3.2 onwards. Check that the "average measures" for the categories advance, and that no category is especially noisy. Use IREFER= and IVALUE= to collapse or remove discordant categories. Use ISGROUPS= to identify category functioning. If more details are required, look at the option/distractor analysis of the Item Tables.


D. Dimensionality: check that all items share the same dimension, same as Table 23. This identifies sub-structures, "secondary dimensions", in the data by performing a principal components/contrast decomposition of the observation residuals. If there are large sub-structures, then it may be wiser to divide the data into two measurement instruments.


E. Item Misfit: check that items cooperate to measure, same as Table 10. Are there misbehaving items? Look for large mean-squares, and also for contradictory use of responses in the option/distractor listing.


F. Construct KeyMap: check that the item hierarchy is as intended (construct validity), same as Table 2.2. This locates items, response categories and your sample in one picture. Does your item measure hierarchy make sense? What is the typical person in your sample saying?


G. Person Misfit: check that persons cooperate to measure, same as Table 6. Are there misbehaving persons? Look for large mean-squares, and also look at the unexpected observations in the Most Unexpected Responses subtable.


H. Separation: check that the items discriminate different levels of person performance ("test" reliability), same as Table 3.1. Also that persons are able to discriminate differences in item calibration.

Help for Winsteps Rasch Measurement Software: www.winsteps.com. Author: John Michael Linacre

For more information, contact info@winsteps.com or use the Contact Form

Facets Rasch measurement software. Buy for $149. & site licenses. Freeware student/evaluation download
Winsteps Rasch measurement software. Buy for $149. & site licenses. Freeware student/evaluation download

State-of-the-art : single-user and site licenses : free student/evaluation versions : download immediately : instructional PDFs : user forum : assistance by email : bugs fixed fast : free update eligibility : backwards compatible : money back if not satisfied
Rasch, Winsteps, Facets online Tutorials


Forum Rasch Measurement Forum to discuss any Rasch-related topic

Click here to add your email address to the Winsteps and Facets email list for notifications.

Click here to ask a question or make a suggestion about Winsteps and Facets software.

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 with Raters and Rating Scales: Rasch Models for Rater-Mediated Assessments, George Engelhard, Jr. & Stefanie Wind 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
Winsteps Tutorials Facets Tutorials Rasch Discussion Groups



Coming Rasch-related Events
April 10-12, 2018, Tues.-Thurs. Rasch Conference: IOMW, New York, NY, www.iomw.org
April 13-17, 2018, Fri.-Tues. AERA, New York, NY, www.aera.net
May 22 - 24, 2018, Tues.-Thur. EALTA 2018 pre-conference workshop (Introduction to Rasch measurement using WINSTEPS and FACETS, Thomas Eckes & Frank Weiss-Motz), https://ealta2018.testdaf.de
May 25 - June 22, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com
June 27 - 29, 2018, Wed.-Fri. Measurement at the Crossroads: History, philosophy and sociology of measurement, Paris, France., https://measurement2018.sciencesconf.org
June 29 - July 27, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Further Topics (E. Smith, Winsteps), www.statistics.com
July 25 - July 27, 2018, Wed.-Fri. Pacific-Rim Objective Measurement Symposium (PROMS), (Preconference workshops July 23-24, 2018) Fudan University, Shanghai, China "Applying Rasch Measurement in Language Assessment and across the Human Sciences" www.promsociety.org
Aug. 10 - Sept. 7, 2018, Fri.-Fri. On-line workshop: Many-Facet Rasch Measurement (E. Smith, Facets), www.statistics.com
Sept. 3 - 6, 2018, Mon.-Thurs. IMEKO World Congress, Belfast, Northern Ireland www.imeko2018.org
Oct. 12 - Nov. 9, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com



Our current URL is www.winsteps.com

Winsteps® is a registered trademark



John "Mike" Linacre, author of Winsteps, and Jenny use and recommend eco-friendly, safe and effective wellness and beauty products such as skincare