Compară metode

	Modelul Logistic IRT cu Doi Parametri (2PL)	Modelul cu Răspunsuri Gradate (GRM)
Domeniu	Psihometrie	Psihometrie
Familie	Latent structure	Latent structure
Anul apariției	1980	1969
Autorul original	Frederic M. Lord	Fumiko Samejima
Tip	Item response model / latent trait model	Item response theory / polytomous IRT model
Sursa seminală	Lord, F. M. (1980). Applications of Item Response Theory to Practical Testing Problems. Erlbaum.	Samejima, F. (1969). Estimation of Latent Ability Using a Response Pattern of Graded Scores. Psychometrika Monograph Supplement, No. 17.
Denumiri alternative	two-parameter logistic model, 2PL model, 2PL IRT — İki Parametreli Madde Tepki Modeli	Samejima's GRM, Derecelendirilmiş Tepki Modeli (GRM), graded IRT model
Înrudite	6	7
Rezumat	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.	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.