by John M. Linacre
MESA Research Note 6, November 1998
The Rasch model is based on the non-linear logistic function. In general, estimates for measures cannot be obtained directly, but must be obtained through a process of improving estimates until they are good enough ("converged"). The process requires performing the same computations over and over again ("iteration").
The iterative process is shorter when:
In one data set with very adverse characteristics, over 600 iterations were required before meaningful estimates were obtained.
In many cases, the estimates are good enough after only a few iterations. A large number of iterations may only be needed for the final, definitive analysis.
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Feb. 28 - June 18, 2022, Mon.-Sat. | On-line course: Introduction to Classical and Rasch Measurement Theories (D. Andrich, I. Marais, RUMM), The Psychometric Laboratory at UWA, Australia |
Feb. 28 - June 18, 2022, Mon.-Sat. | On-line course: Advanced Course in Rasch Measurement Theory (D. Andrich, I. Marais, RUMM), The Psychometric Laboratory at UWA, Australia |
May 20 - June 17, 2022, Fri.-Fri. | On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com |
June 24 - July 22, 2022, Fri.-Fri. | On-line workshop: Practical Rasch Measurement - Further Topics (E. Smith, Winsteps), www.statistics.com |
Aug. 12 - Sept. 9, 2022, Fri.-Fri. | On-line workshop: Many-Facet Rasch Measurement (E. Smith, Facets), www.statistics.com |
Oct. 7 - Nov. 4, 2022, Fri.-Fri. | On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com |
June 23 - July 21, 2023, Fri.-Fri. | On-line workshop: Practical Rasch Measurement - Further Topics (E. Smith, Winsteps), www.statistics.com |
Aug. 11 - Sept. 8, 2023, Fri.-Fri. | On-line workshop: Many-Facet Rasch Measurement (E. Smith, Facets), www.statistics.com |
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