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	Graded Response Model (GRM)	部分評点モデル（PCM / GPCM）
分野	心理測定学	心理測定学
系統	Latent structure	Latent structure
提唱年	1969	1982
提唱者	Fumiko Samejima	Geoff N. Masters (PCM, 1982); Eiji Muraki (GPCM, 1992)
種類	Item response theory / polytomous IRT model	Item Response Theory / Polytomous IRT
原典	Samejima, F. (1969). Estimation of Latent Ability Using a Response Pattern of Graded Scores. Psychometrika Monograph Supplement, No. 17.	Masters, G. N. (1982). A Rasch model for partial credit scoring. Psychometrika, 47(2), 149–174.
別名	Samejima's GRM, Derecelendirilmiş Tepki Modeli (GRM), graded IRT model	Kısmi Kredi Modeli (PCM / GPCM), Generalized Partial Credit Model, GPCM, PCM
関連	7	5
概要	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 Partial Credit Model is an extension of the Rasch measurement framework designed for ordered polytomous items — items whose responses fall into more than two ordered categories, such as partial-credit tasks in performance assessment or open-ended scoring rubrics. Proposed by Geoff Masters in 1982 and later generalised by Eiji Muraki in 1992, the model estimates a separate threshold (step) parameter for each adjacent-category transition within every item, allowing fine-grained calibration of how much each additional credit level contributes to locating a person on the latent trait.