手法を比較

	順序尺度の開発	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	1932 (Likert format); 1990s–2000s (ordinal-specific psychometric methods)	1952–1968
提唱者	Rensis Likert (foundational ordinal response format); modern ordinal methodology codified by DeVellis and Finney & DiStefano	Frederic M. Lord (and Allan Birnbaum for the 2PL/3PL models)
種類	Scale construction methodology	Probabilistic measurement model
原典	DeVellis, R. F. (2017). Scale Development: Theory and Applications (4th ed.). SAGE Publications. ISBN: 978-1506341569	Lord, F. M. & Novick, M. R. (1968). Statistical Theories of Mental Test Scores. Addison-Wesley.
別名	Likert scale development, ordinal measurement scale construction, ordinal item development, polytomous scale construction	IRT, latent trait theory, item characteristic curve theory, modern test theory
関連	5	5
概要	Ordinal scale development is the systematic construction and validation of multi-item measurement instruments whose response options form an ordered but not necessarily equal-interval sequence — most commonly Likert-type formats (e.g., 1 = Strongly Disagree to 5 = Strongly Agree). It applies psychometric techniques that respect the ordinal nature of items rather than treating them as continuous.	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.