Table 8 Scale structure bar-chart

This gives several pictorial representations of the rating scale (or partial credit).

 

Scale structure for "FACES"

Measr:-3.0       -2.0       -1.0        0.0        1.0        2.0        3.0

       +          +          +          +          +          +          +

 Mode:<0---------(^)----------01--------^-------12-----------(^)---------2>

 

Median:<0---------(^)--------01----------^---------12---------(^)---------2>

 

 Mean:<0---------(^)------01------------^-----------12--------(^)--------2>

       +          +          +          +          +          +          +

Measr:-3.0       -2.0       -1.0        0.0        1.0        2.0        3.0

 

Mode: Most Probable Category

 

The values are relative to the relevant item difficulty.

The category labels are located at the measures where they commence to be the most probable observations. Omitted categories are never most probable. ^ indicates location of category peak probability. (^) indicates point at which extreme category becomes very probable.

Median: Rasch-Thurstone Threshold

 

The values are relative to the relevant item difficulty.

The category labels are located at the measures where there is the same probability (0.5) of being rated below that category as there is of being rated in that category or above. Conceptually, each category label is at the left-hand end of its "zone" on the variable. ^ indicate the mid-points of each zone. (^) indicates a conceptual mid-point of the infinitely long extreme zones.

Mean: Expected Score

 

The values are relative to the relevant item difficulty.

 

The mean values are usually more dispersed than the median, and the median than the mode.

The category labels are located at the measures where the expected values become closer to that score than the preceding score, i.e., at the half score-points. ^ indicates the locations where the category score is the expected score. (^) indicates the location at which the expected score is 0.25 score points away from the extreme category score.

the "mean" values below Table 8.2 (shown above) are the "scale" values on the right side of Table 6.0, and are the "Expectation" measures in Table 8.1. They answer the question: if we had 1,000 people at a particular measure relative to the item difficulty, what would we expect their average (mean) rating to be?

Measr: Measure relative to item difficulty

The scale of relative measures, e.g., persons relative to an item. The local origin is the mean of the Rasch-Andrich thresholds (step calibrations) or as determined by the anchored categories.

 

Dichotomous scale structures are always the same:

 

Scale structure for dichotomies

 

Measr:-2.0             -1.0              0.0              1.0              2.0

       +                +                +                +                +

 Mode:<0--------------------------------(^)--------------------------------0>

 

Median:<0--------------------------------(^)--------------------------------0>

 

 Mean:<0--------------------------------(^)--------------------------------0>

       +                +                +                +                +

Measr:-2.0             -1.0              0.0              1.0              2.0


Help for Facets 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
Jan. 5 - Feb. 2, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com
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
Jan. 22-24, 2018, Mon-Wed. In-person workshop: Rasch Measurement for Everybody en español (A. Tristan, Winsteps), San Luis Potosi, Mexico. www.ieia.com.mx
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
 

Concerned about aches, pains, youthfulness? Mike and Jenny suggest Liquid Biocell