How big an analysis can I do? |
Winsteps will operate with a minimum of two observations per item or person, or even 1 observation with anchoring. This is useful for producing score tables with anchored items and dummy response strings. For statistically stable measures to be estimated, 30 observations per element (item or person) are needed: www.rasch.org/rmt/rmt74m.htm
The maximum number of reportable persons is 9,999,999 persons. The maximum number of items (NI=) is near 65,000 items. The maximum length of an item or person label is 300 ASCII characters. The maximum printable line is 3,003 characters. Exam18.txt is an example of a large data set.
There can be up to 32,768 ordinally numbered categories per item (polytomies, rating scales, partial credit etc.).
Subset evaluation: up to 50,000 potential subsets, depending on available computer memory.
The widest logit range of measures that maintains computational precision is 90 logits, but useful results can be reported with a measure range up to 700 logits wide.
In order to maintain high computational precision, while maintaining computational speed, Winsteps implements West, D.H.D. (1979), "Updating Mean and Variance Estimates An Improved Method," Communications of the Association for Computing Machinery, 22, 532-535.
Example: a dataset of almost 500,000 persons and 20,000 items was analyzed with Winsteps. The data were 99% missing. This type of analysis can take several hours, depending on your computer hardware.
Help for Winsteps Rasch Measurement and Rasch Analysis Software: www.winsteps.com. Author: John Michael Linacre
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Coming Rasch-related Events | |
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May 17 - June 21, 2024, Fri.-Fri. | On-line workshop: Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com |
June 12 - 14, 2024, Wed.-Fri. | 1st Scandinavian Applied Measurement Conference, Kristianstad University, Kristianstad, Sweden http://www.hkr.se/samc2024 |
June 21 - July 19, 2024, Fri.-Fri. | On-line workshop: Rasch Measurement - Further Topics (E. Smith, Winsteps), www.statistics.com |
Aug. 5 - Aug. 6, 2024, Fri.-Fri. | 2024 Inaugural Conference of the Society for the Study of Measurement (Berkeley, CA), Call for Proposals |
Aug. 9 - Sept. 6, 2024, Fri.-Fri. | On-line workshop: Many-Facet Rasch Measurement (E. Smith, Facets), www.statistics.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 |
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