Let us use the notation of Rating Scale Analysis (Wright & Masters, 1982)
p. 100
Xni = the observation generated by person n on item i
Eni = its expectation = sum k*Pnik, for k = 0,m
Yni = its residual = Xni - Eni
Wni = its variance = sum (k*k*Pnik) - Eni*Eni, for k = 0,m
Then the logit bias for subset S of persons on item i is
Bias(S) = sum (Yni) / sum (Wni) where sum is across all n in S
Standard error of Bias is
SE (S) = sqrt ( sum (Wni) ) where sum is across all n in S
Statistical significance of Logit Bias departure from its expectation of 0.0 is
t = Bias(S)/SE(S)
MESA Research Note #1 by John Michael Linacre, April 1997
Go to Top of Page
Go to Institute for Objective Measurement Page
Coming Rasch-related Events | |
---|---|
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 |
Our current URL is www.rasch.org
The URL of this page is www.rasch.org/rn1.htm