Zeroes: Structural and Incidental: Ordinal or Keep

This is for 32-bit Facets 3.87. Here is Help for 64-bit Facets 4

Unobserved categories can be dropped from rating scales (or partial credit items) and the remaining category recounted during estimation. For intermediate categories only, recounting can be prevented and unobserved categories retained in the analysis. This is useful when the unobserved categories are important to the rating scale (or partial credit) logic or are usually observed, even though they happen to have been unused this time. Category transitions for which anchor Rasch-Andrich threshold-values (step calibrations) are supplied are always maintained wherever computationally possible, even when there are no observations of a category in the current data set.

 

Use "Rating Scale= .... Keep" when there may be intermediate categories in your rating scale (or partial credit) that aren't observed in this data set, i.e., incidental zeroes.

 

Use "Rating Scale= .... Ordinal" when your category numbering deliberately skips over intermediate categories, i.e., structural zeroes.

 

"Rating Scale= .... Ordinal" Eliminate unused categories and close up the observed categories.

 

"Rating Scale= .... Keep" Retain unused non-extreme categories in the ordinal categorization.

 

When "Rating Scale= .... Keep", missing categories are retained in the rating scale (or partial credit), so maintaining the raw score ordering. But missing categories require arbitrarily extreme Rasch-Andrich thresholds. If these threshold values are to be used for anchoring later runs, compare these thresholds with the thresholds obtained by an unanchored analysis of the new data. This will assist you in determining what adjustments need to be made to the original threshold-values in order to establish a set of anchor threshold-values that maintain the same rating scale (or partial credit) structure.

 

Example 1: Incidental unobserved categories. Keep the developmentally important rating scale (or partial credit) categories, observed or not. Your small Piaget scale goes from 1 to 6. But some levels may not have been observed in this data set.

 Models = ?,?,?, Piagetscale

 Rating Scale = Piagetscale, R6, Keep

 

Example 2: Structural unobserved categories. Responses have been coded as "10", "20", "30", "40", but they really mean 1,2,3,4  

 Models = ?, ?, ?, Tensscale

 Rating Scale = Tensscale, R40, Ordinal

 ; if "Rating Scale= .... Keep", then data are analyzed as though categories 11, 12, 13, 14, etc. could exist, which would distort the measures.

 ; for reporting purposes, multiply Facets reported raw scores by 10 to return to the original 10, 20, 30 categorization.

 

Example 3: Some unobserved categories are structural and some incidental. Rescore the data and use "Rating Scale= .... Keep". Possible categories are 2,4,6,8 but only 2,6,8 are observed this time.

 (a) Rescore 2,4,6,8 to 1,2,3,4  

 (b) Set "Rating Scale= .... Keep", so that the observed 1,3,4 and unobserved 2 are treated as 1,2,3,4

 (c) For reporting purposes, multiply the reported Facets scores by 2 using Excel or similar software.

 Models = ?,?,?,Evenscale

 Rating Scale = Evenscale, R8, Keep

 1 = original 2, , , 2

 2 = original 4, , , 4

 3 = original 6, , , 6

 4 = original 8, , , 8

 *

 


 

Incidental and Structural Zeroes: Extreme and Intermediate

 

For missing intermediate categories, there are two options.

 

If the categories are missing because they cannot be observed, then they are "structural zeroes". Specify "Rating Scale= .... Ordinal". This effectively recounts the observed categories starting from the bottom category, so that 1,3,5,7 becomes 1,2,3,4.

 

If they are missing because they just do not happen to have been observed this time, then they are "incidental or sampling zeros". Specify "Rating Scale= .... Keep". Then 1,3,5,7 is treated as 1,2,3,4,5,6,7.

 

Categories outside the observed range are always treated as structural zeroes.

 

When "Rating Scale= .... Keep", unobserved intermediate categories are imputed using a mathematical device noticed by Mark Wilson. This device can be extended to runs of unobserved categories.


Help for Facets Rasch Measurement and Rasch Analysis Software: www.winsteps.com Author: John Michael Linacre.
 

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

Rasch Books and Publications
Invariant Measurement: Using Rasch Models in the Social, Behavioral, and Health Sciences, 2nd Edn, 2024 George Engelhard, Jr. & Jue Wang Applying the Rasch Model (Winsteps, Facets) 4th Ed., Bond, Yan, Heene Advances in Rasch Analyses in the Human Sciences (Winsteps, Facets) 1st Ed., Boone, Staver Advances in Applications of Rasch Measurement in Science Education, X. Liu & W. J. Boone Rasch Analysis in the Human Sciences (Winsteps) Boone, Staver, Yale
Introduction to Many-Facet Rasch Measurement (Facets), Thomas Eckes Statistical Analyses for Language Testers (Facets), Rita Green Invariant Measurement with Raters and Rating Scales: Rasch Models for Rater-Mediated Assessments (Facets), George Engelhard, Jr. & Stefanie Wind Aplicação do Modelo de Rasch (Português), de Bond, Trevor G., Fox, Christine M Appliquer le modèle de Rasch: Défis et pistes de solution (Winsteps) E. Dionne, S. Béland
Exploring Rating Scale Functioning for Survey Research (R, Facets), Stefanie Wind Rasch Measurement: Applications, Khine Winsteps Tutorials - free
Facets Tutorials - free
Many-Facet Rasch Measurement (Facets) - free, J.M. Linacre Fairness, Justice and Language Assessment (Winsteps, Facets), McNamara, Knoch, Fan
Other Rasch-Related Resources: Rasch Measurement YouTube Channel
Rasch Measurement Transactions & Rasch Measurement research papers - free An Introduction to the Rasch Model with Examples in R (eRm, etc.), Debelak, Strobl, Zeigenfuse Rasch Measurement Theory Analysis in R, Wind, Hua Applying the Rasch Model in Social Sciences Using R, Lamprianou El modelo métrico de Rasch: Fundamentación, implementación e interpretación de la medida en ciencias sociales (Spanish Edition), Manuel González-Montesinos M.
Rasch Models: Foundations, Recent Developments, and Applications, Fischer & Molenaar Probabilistic Models for Some Intelligence and Attainment Tests, Georg Rasch Rasch Models for Measurement, David Andrich Constructing Measures, Mark Wilson Best Test Design - free, Wright & Stone
Rating Scale Analysis - free, Wright & Masters
Virtual Standard Setting: Setting Cut Scores, Charalambos Kollias Diseño de Mejores Pruebas - free, Spanish Best Test Design A Course in Rasch Measurement Theory, Andrich, Marais Rasch Models in Health, Christensen, Kreiner, Mesba Multivariate and Mixture Distribution Rasch Models, von Davier, Carstensen
As an Amazon Associate I earn from qualifying purchases. This does not change what you pay.

facebook Forum: Rasch Measurement Forum to discuss any Rasch-related topic

To receive News Emails about Winsteps and Facets by subscribing to the Winsteps.com email list,
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 Winsteps.com
The Winsteps.com email list is only used to email information about Winsteps, Facets and associated Rasch Measurement activities. Your email address is not shared with third-parties. Every email sent from the list includes the option to unsubscribe.

Questions, Suggestions? Want to update Winsteps or Facets? Please email Mike Linacre, author of Winsteps mike@winsteps.com


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

Coming Rasch-related Events: Winsteps and Facets
Oct 21 - 22 2024, Mon.-Tues. In person workshop: Facets and Winsteps in expert judgement test validity - UNAM (México) y Universidad Católica de Colombia. capardo@ucatolica.edu.co, benildegar@gmail.com
Oct. 4 - Nov. 8, 2024, Fri.-Fri. On-line workshop: Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com
Jan. 17 - Feb. 21, 2025, Fri.-Fri. On-line workshop: Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com
May 16 - June 20, 2025, Fri.-Fri. On-line workshop: Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com
June 20 - July 18, 2025, Fri.-Fri. On-line workshop: Rasch Measurement - Further Topics (E. Smith, Facets), www.statistics.com
Oct. 3 - Nov. 7, 2025, Fri.-Fri. On-line workshop: Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com

 

Our current URL is www.winsteps.com

Winsteps® is a registered trademark