Methoden vergleichen

	Cronbachs Alpha bei computergestützten adaptiven Tests	Item Response Theory (IRT)
Fachgebiet	Psychometrie	Psychometrie
Familie	Latent structure	Latent structure
Entstehungsjahr	1984	1952–1968
Urheber	Adapted from Cronbach (1951); CAT reliability framing developed by Green, Bock, Humphreys, Linn & Reckase (1984)	Frederic M. Lord (and Allan Birnbaum for the 2PL/3PL models)
Typ	Reliability / internal consistency estimation	Probabilistic measurement model
Wegweisende Quelle	Green, B. F., Bock, R. D., Humphreys, L. G., Linn, R. L., & Reckase, M. D. (1984). Technical guidelines for assessing computerized adaptive tests. Journal of Educational Measurement, 21(4), 347–360.	Lord, F. M. & Novick, M. R. (1968). Statistical Theories of Mental Test Scores. Addison-Wesley.
Aliasnamen	CAT reliability estimation, adaptive test internal consistency, CAT coefficient alpha, reliability in CAT	IRT, latent trait theory, item characteristic curve theory, modern test theory
Verwandt	3	5
Zusammenfassung	Cronbach's alpha applied to computerized adaptive test (CAT) data estimates internal consistency reliability under the special condition that different examinees receive different subsets of items. Because the classic formula assumes every respondent answers the same items, its direct application to CAT data violates core assumptions and typically underestimates or misrepresents true reliability, requiring careful adaptation or replacement with IRT-based reliability indices.	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.