Stable estimates of item calibration are important and the results should be consistent using different software programs for research to progress satisfactorily. Items tend to greater consistency although produced by person responses (Fisher, 2010). The database of 3,121 persons and 26 items for the KCT-R (Stone, 2002) produced a test separation value of 38.22 corresponding to a test reliability of 0.99. The person separation value was 2.54 corresponding to a person reliability of 0.87. A sample of 260 persons ages 5 – 60 produced a test-retest coefficient of 0.96.
Two programs for producing estimations - Winsteps (Linacre, 2002) and RUMM (Andrich, D., et al., 2000) - were utilized. A well-defined variable and wide item/ability logit range made the KCT-R data useful for this comparison. Newer releases provide additional enhancements, but the basic estimation algorithms remain constant.
Figure 1 is a plot of item calibration estimations using Winsteps and RUMM2010. This figure accents the differences. The Winsteps estimates were lower than the estimates using RUMM2010 for items 1 – 12, and slightly higher for items 13 – 26. A difference of about 0.8 logits was observed for the two easiest items of the test. These differences decreased to item 12. They reversed thereafter with the difference continuing to about 0.3 for the most difficult items.
Figure 2 identifies the stability in the estimations. The lowest four calibration estimates show the largest deviations that diminish towards 0.0 and then increase with the highest two calibration estimates showing the greatest difference. In spite of the noted differences between the two software programs, the item calibration estimates are highly correlated. The wide-range of the calibration estimates contributes to a high r2 of 0.99, but with Winsteps estimates slightly more extreme than RUMM2010 estimates. Stability exists between the two estimations processes with the differences well within any meaningful difference. Nevertheless, a slight difference exists in the estimation process.
American Institutes for Research
Collaborative for Research on Outcomes and Metrics
Aurora University, Aurora, IL
Andrich, D., Lyne, A., Sheridan, B., & Luo, G. (2000). RUMM 2010: Rasch Unidimensional Measurement Models. Australia: Rumm Laboratory Try Ltd.
Fisher, W. P., Jr. (2010, 30 September). Distinguishing between consistency and error in reliability coefficients: Improving the estimation and interpretation of information on measurement precision. Social Science Research Network. Retrieved from http://ssrn.com/abstract=1685556.
Linacre, J. M. (2003). Winsteps. Beaverton Oregon: Winsteps.com.
Figure 1. A plot of item calibration estimates using Winsteps and RUMM2010. Points on the solid line are RUMM estimates. Points on the dashed line are Winsteps estimates. The y-axis is "Difficulty in Logits"
Figure 2. A cross-plot of the KCT-R items calibration estimates using Winsteps (y-axis) and RUMM2010 (x-axis) .
Comparing Item Calibration Estimates using Winsteps and RUMM2010, Futoshi Yumoto & Mark Stone ... Rasch Measurement Transactions, 2011, 25:3, 1329
Please help with Standard Dataset 4: Andrich Rating Scale Model
|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|
|Forum||Rasch 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, www.rasch.org.
|Coming Rasch-related Events|
|Feb. 27 - June 24, 2017, Mon.-Sat.||On-line: Advanced course in Rasch Measurement Theory (EDUC5606), Website|
|March 31, 2017, Fri.||Conference: 11th UK Rasch Day, Warwick, UK, www.rasch.org.uk|
|April 2-3, 2017, Sun.-Mon.||Conference: Validity Evidence for Measurement in Mathematics Education (V-M2Ed), San Antonio, TX, Information|
|April 26-30, 2017, Wed.-Sun.||NCME, San Antonio, TX, www.ncme.org|
|April 27 - May 1, 2017, Thur.-Mon.||AERA, San Antonio, TX, www.aera.net|
|May 26 - June 23, 2017, Fri.-Fri.||On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com|
|June 30 - July 29, 2017, Fri.-Fri.||On-line workshop: Practical Rasch Measurement - Further Topics (E. Smith, Winsteps), www.statistics.com|
|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, imeko-tc7-rio.org.br|
|Aug. 7-9, 2017, Mon-Wed.||PROMS 2017: Pacific Rim Objective Measurement Symposium, Sabah, Borneo, Malaysia, proms.promsociety.org/2017/|
|Aug. 11 - Sept. 8, 2017, Fri.-Fri.||On-line workshop: Many-Facet Rasch Measurement (E. Smith, Facets), www.statistics.com|
|Aug. 18-21, 2017, Fri.-Mon.||IACAT 2017: International Association for Computerized Adaptive Testing, Niigata, Japan, iacat.org|
|Sept. 15-16, 2017, Fri.-Sat.||IOMC 2017: International Outcome Measurement Conference, Chicago, jampress.org/iomc2017.htm|
|Oct. 13 - Nov. 10, 2017, Fri.-Fri.||On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com|
|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|
|May 25 - June 22, 2018, Fri.-Fri.||On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com|
|June 29 - July 27, 2018, Fri.-Fri.||On-line workshop: Practical Rasch Measurement - Further Topics (E. Smith, Winsteps), www.statistics.com|
|Aug. 10 - Sept. 7, 2018, Fri.-Fri.||On-line workshop: Many-Facet Rasch Measurement (E. Smith, Facets), www.statistics.com|
|Oct. 12 - Nov. 9, 2018, Fri.-Fri.||On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com|
|The HTML to add "Coming Rasch-related Events" to your webpage is:|