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	Funzionamento Differenziale Ordinato degli Item (DIF Ordinato)	Teoria della risposta all'item (IRT)
Campo	Psicometria	Psicometria
Famiglia	Latent structure	Latent structure
Anno di origine	1999-2001	1952–1968
Ideatore	Zumbo (logistic extension) and Penfield (Mantel generalization)	Frederic M. Lord (and Allan Birnbaum for the 2PL/3PL models)
Tipo	Item bias detection for ordered-category items	Probabilistic measurement model
Fonte seminale	Zumbo, B. D. (1999). A handbook on the theory and methods of differential item functioning (DIF): Logistic regression modeling as a unitary framework for binary and Likert-type (ordinal) item scores. Ottawa: Directorate of Human Resources Research and Evaluation, Department of National Defense.	Lord, F. M. & Novick, M. R. (1968). Statistical Theories of Mental Test Scores. Addison-Wesley.
Alias	ordinal DIF, polytomous DIF, DIF for ordered categories, ordinal logistic DIF	IRT, latent trait theory, item characteristic curve theory, modern test theory
Correlati	6	5
Sintesi	Ordinal differential item functioning analysis detects whether an ordered-category item (such as a Likert-scale question) functions differently across demographic or cultural groups after controlling for the latent trait being measured. It extends classical binary DIF methods to polytomous response formats common in psychological and educational scales.	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.