방법 비교

	3모수 로지스틱 문항반응이론 모형 (3PL)	2모수 로지스틱 문항반응 이론 모형 (2PL)
분야	심리측정학	심리측정학
계열	Latent structure	Latent structure
기원 연도	1968	1980
창시자	Allan Birnbaum	Frederic M. Lord
유형	Item response model / latent trait model	Item response model / latent trait model
원전	Birnbaum, A. (1968). Some latent trait models and their use in inferring an examinee's ability. In F. M. Lord & M. R. Novick (Eds.), Statistical theories of mental test scores (pp. 397–479). Addison-Wesley.	Lord, F. M. (1980). Applications of Item Response Theory to Practical Testing Problems. Erlbaum.
별칭	3PL IRT — Üç Parametreli Madde Tepki Modeli, three-parameter logistic model, 3PLM, Birnbaum model	two-parameter logistic model, 2PL model, 2PL IRT — İki Parametreli Madde Tepki Modeli
관련	5	6
요약	The three-parameter logistic (3PL) model, introduced by Allan Birnbaum in 1968, is an item response theory model that describes the probability of a correct response to a binary test item as a function of three item-level parameters — difficulty, discrimination, and a lower asymptote representing guessing — and one person-level parameter representing latent ability.	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.