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	Ordinal differential item functioning (Ordinal DIF)	Ordinal tillförlitlighetsanalys
Ämnesområde	Psykometri	Psykometri
Familj	Latent structure	Latent structure
Ursprungsår	1999-2001	2007
Upphovsperson	Zumbo (logistic extension) and Penfield (Mantel generalization)	Bruno D. Zumbo and colleagues
Typ	Item bias detection for ordered-category items	Internal consistency reliability estimation
Ursprungskälla	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.	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.
Alias	ordinal DIF, polytomous DIF, DIF for ordered categories, ordinal logistic DIF	ordinal alpha, polychoric reliability, reliability for ordinal scales, ORA
Närliggande	6	5
Sammanfattning	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.	Ordinal reliability analysis estimates the internal consistency of scales whose items are measured on ordered-category (Likert-type) response formats. By basing computations on polychoric correlations rather than Pearson correlations, it corrects for the attenuation that standard Cronbach's alpha produces when responses are discrete and non-normal.