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
| FORUM | Rasch Measurement Forum to discuss any Rasch-related topic |
| Coming Rasch-related Events | |
|---|---|
| Jan. 16 - Feb. 13, 2025, Fri.-Fri. | On-line workshop: Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com |
| Apr. 8 - Apr. 11, 2026, Wed.-Sat. | National Council for Measurement in Education - Los Angeles, CA, ncme.org/events/2026-annual-meeting |
| Apr. 8 - Apr. 12, 2026, Wed.-Sun. | American Educational Research Association - Los Angeles, CA, www.aera.net/AERA2026 |
| May. 15 - June 12, 2026, Fri.-Fri. | On-line workshop: Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com |
| June 19 - July 25, 2026, Fri.-Sat. | On-line workshop: Rasch Measurement - Further Topics (E. Smith, Winsteps), www.statistics.com |
Our current URL is www.rasch.org
The URL of this page is www.rasch.org/rn1.htm