So sánh phương pháp

	Mô hình Rasch Đa hạng	Chức năng biệt lập của mục (Differential Item Functioning - DIF)
Lĩnh vực	Trắc lượng tâm lý	Trắc lượng tâm lý
Họ	Latent structure	Latent structure
Năm ra đời	1978–1982	1970s–1993
Người khởi xướng	Gerhard N. Masters (Partial Credit Model); David Andrich (Rating Scale Model)	William H. Angoff and colleagues (ETS); systematized by Holland & Wainer
Loại	Item response model	Item-level bias detection
Công trình gốc	Masters, G. N. (1982). A Rasch model for partial credit scoring. Psychometrika, 47(2), 149–174.	Holland, P. W. & Wainer, H. (Eds.) (1993). Differential Item Functioning. Lawrence Erlbaum Associates. ISBN: 978-0805809589
Tên gọi khác	PRM, Rating Scale Model, Partial Credit Model, Polytomous IRT Rasch	DIF, item bias analysis, measurement non-equivalence, item-level measurement bias
Liên quan	6	5
Tóm tắt	The Polytomous Rasch Model extends the dichotomous Rasch framework to ordered response scales with three or more categories, such as Likert items or partial-credit tasks. It estimates person ability and item difficulty on the same interval-level logit scale, and it tests whether the response categories function as intended — prerequisites for rigorous ordinal measurement.	Differential item functioning identifies test or survey items that behave differently for examinees from different groups — such as gender, ethnicity, or language background — after controlling for the underlying ability or trait being measured. DIF analysis is essential for fairness evaluation in educational testing and psychological scale development.