Methoden vergleichen

	McDonalds Omega für computergestützte adaptive Tests	Cronbachs Alpha bei computergestützten adaptiven Tests
Fachgebiet	Psychometrie	Psychometrie
Familie	Latent structure	Latent structure
Entstehungsjahr	1999 (omega); CAT application 2000s–2010s	1984
Urheber	Roderick P. McDonald (omega); CAT-omega application extended by IRT and psychometric reliability researchers	Adapted from Cronbach (1951); CAT reliability framing developed by Green, Bock, Humphreys, Linn & Reckase (1984)
Typ	Reliability coefficient for adaptive tests	Reliability / internal consistency estimation
Wegweisende Quelle	McDonald, R. P. (1999). Test Theory: A Unified Treatment. Lawrence Erlbaum Associates. ISBN: 978-0805830408	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.
Aliasnamen	CAT omega reliability, omega in adaptive testing, hierarchical omega for CAT, CAT composite reliability	CAT reliability estimation, adaptive test internal consistency, CAT coefficient alpha, reliability in CAT
Verwandt	5	3
Zusammenfassung	McDonald's omega adapted for computerized adaptive testing (CAT) quantifies the reliability of ability or trait estimates when different examinees answer different subsets of items. Unlike Cronbach's alpha, omega is grounded in a factor model, making it suitable for the heterogeneous item pools and variable test lengths that characterize adaptive administrations.	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.