Methoden vergelijken

	Short-Form Differential Item Functioning (Short-Form DIF)	Item Response Theory (IRT)
Vakgebied	Psychometrie	Psychometrie
Familie	Latent structure	Latent structure
Jaar van ontstaan	1970s–1990s (DIF); short-form context developed in parallel with scale abbreviation literature	1952–1968
Grondlegger	Angoff, W. H. and subsequent DIF methodologists	Frederic M. Lord (and Allan Birnbaum for the 2PL/3PL models)
Type	Item bias / measurement fairness analysis	Probabilistic measurement model
Oorspronkelijke bron	Millsap, R. E. (2012). Statistical Approaches to Measurement Invariance. Routledge. ISBN: 978-0-8058-4507-0	Lord, F. M. & Novick, M. R. (1968). Statistical Theories of Mental Test Scores. Addison-Wesley.
Aliassen	Short-form DIF, abbreviated scale DIF, DIF in short forms, short-scale DIF detection	IRT, latent trait theory, item characteristic curve theory, modern test theory
Verwant	6	5
Samenvatting	Short-form differential item functioning (DIF) analysis examines whether individual items in an abbreviated scale function equivalently across demographic or subgroup comparisons. When a scale is shortened, retained items must still behave fairly for all relevant groups — DIF analysis verifies this, ensuring that score differences reflect true ability or trait differences rather than item bias.	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.