手法を比較

	短縮版クロンバックのα	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	1951 (alpha); short-form practice codified 1980s–2000s	1952–1968
提唱者	L. J. Cronbach (alpha); short-form application formalized across scale-abbreviation literature	Frederic M. Lord (and Allan Birnbaum for the 2PL/3PL models)
種類	Internal consistency reliability coefficient	Probabilistic measurement model
原典	Smith, G. T., McCarthy, D. M. & Anderson, K. G. (2000). On the sins of short-form development. Psychological Assessment, 12(1), 102–111.	Lord, F. M. & Novick, M. R. (1968). Statistical Theories of Mental Test Scores. Addison-Wesley.
別名	abbreviated scale alpha, brief scale internal consistency, short-scale Cronbach's alpha, reduced-item alpha	IRT, latent trait theory, item characteristic curve theory, modern test theory
関連	4	5
概要	Short-form Cronbach's alpha quantifies the internal consistency reliability of an abbreviated version of a psychological scale. It applies Cronbach's alpha formula to a reduced item set, verifying that the shortened instrument retains sufficient reliability to support valid score interpretation in research and applied contexts.	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.