Methoden vergleichen

	Graded Response Model (GRM)	Zweiparametrisches logistisches IRT-Modell (2PL)
Fachgebiet	Psychometrie	Psychometrie
Familie	Latent structure	Latent structure
Entstehungsjahr	1969	1980
Urheber	Fumiko Samejima	Frederic M. Lord
Typ	Item response theory / polytomous IRT model	Item response model / latent trait model
Wegweisende Quelle	Samejima, F. (1969). Estimation of Latent Ability Using a Response Pattern of Graded Scores. Psychometrika Monograph Supplement, No. 17.	Lord, F. M. (1980). Applications of Item Response Theory to Practical Testing Problems. Erlbaum.
Aliasnamen	Samejima's GRM, Derecelendirilmiş Tepki Modeli (GRM), graded IRT model	two-parameter logistic model, 2PL model, 2PL IRT — İki Parametreli Madde Tepki Modeli
Verwandt	7	6
Zusammenfassung	The Graded Response Model is an item response theory model developed by Fumiko Samejima in 1969 for ordered polytomous items such as Likert-type scales. It estimates both the discriminating power of each item and a set of threshold parameters marking the boundaries between adjacent response categories, while simultaneously placing persons on a continuous latent trait scale.	The two-parameter logistic item response model, formalised by Frederic Lord (1980), describes the probability that a respondent answers a binary test item correctly as a smooth S-shaped function of the respondent's latent ability. By estimating a separate discrimination parameter for each item alongside a difficulty parameter, 2PL allows items to differ in how sharply they distinguish high- from low-ability respondents — making it the standard model for large-scale educational and psychological assessments.