手法を比較

	Ordinal McDonald's Omega	項目応答理論 (IRT)
分野	心理測定学	心理測定学
系統	Latent structure	Latent structure
提唱年	2007	1952–1968
提唱者	Bruno D. Zumbo, Anne M. Gadermann, and Cornelia Zeisser (building on McDonald's 1999 omega framework)	Frederic M. Lord (and Allan Birnbaum for the 2PL/3PL models)
種類	Reliability coefficient	Probabilistic measurement model
原典	Zumbo, B. D., Gadermann, A. M., & Zeisser, C. (2007). Ordinal versions of coefficients alpha and theta as measures of internal consistency for Likert rating scales. Journal of Modern Applied Statistical Methods, 6(1), 21–29.	Lord, F. M. & Novick, M. R. (1968). Statistical Theories of Mental Test Scores. Addison-Wesley.
別名	omega ordinal, ordinal omega, polychoric omega, omega for ordinal data	IRT, latent trait theory, item characteristic curve theory, modern test theory
関連	3	5
概要	Ordinal McDonald's omega is a reliability coefficient designed for Likert-type and other ordinal rating scales. Unlike Cronbach's alpha, it bases its calculation on polychoric correlations among items — capturing the true latent relationships between ordinal responses — and uses factor-analytic loadings to estimate how much of the composite score variance is attributable to a common factor.	Item response theory models the probability that a respondent answers an item correctly (or endorses it) as a function of the respondent's latent trait level and the item's own statistical properties — difficulty, discrimination, and guessing. Unlike classical test theory, IRT places persons and items on the same scale, yielding measurement that is sample-independent for items and test-independent for persons.