手法を比較

	2母数ロジスティックIRTモデル（2PL）	3パラメータロジスティックIRTモデル（3PL）
分野	心理測定学	心理測定学
系統	Latent structure	Latent structure
提唱年	1980	1968
提唱者	Frederic M. Lord	Allan Birnbaum
種類	Item response model / latent trait model	Item response model / latent trait model
原典	Lord, F. M. (1980). Applications of Item Response Theory to Practical Testing Problems. Erlbaum.	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.
別名	two-parameter logistic model, 2PL model, 2PL IRT — İki Parametreli Madde Tepki Modeli	3PL IRT — Üç Parametreli Madde Tepki Modeli, three-parameter logistic model, 3PLM, Birnbaum model
関連	6	5
概要	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 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.