手法を比較

	多カテゴリ項目信頼性分析	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	2007–2009 (formal ordinal extensions); broader framework since 1950s	1952–1968
提唱者	Building on Cronbach (1951) and McDonald (1978); ordinal extensions by Zumbo and colleagues (2007) and Green and Yang (2009)	Frederic M. Lord (and Allan Birnbaum for the 2PL/3PL models)
種類	Reliability estimation	Probabilistic measurement model
原典	Green, S. B. & Yang, Y. (2009). Reliability of summed item scores using structural equation modeling: An alternative to coefficient alpha. Psychometrika, 74(1), 155–167.	Lord, F. M. & Novick, M. R. (1968). Statistical Theories of Mental Test Scores. Addison-Wesley.
別名	polytomous scale reliability, ordinal reliability estimation, reliability for ordered-category items, polychoric reliability analysis	IRT, latent trait theory, item characteristic curve theory, modern test theory
関連	3	5
概要	Polytomous reliability analysis estimates the internal consistency or precision of measurement for scales composed of items with more than two ordered response categories, such as Likert-type, rating, or partial-credit items. It corrects a well-known underestimation bias in conventional Cronbach's alpha by working with polychoric correlations or IRT-based precision indices.	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.