So sánh phương pháp

	Thiết kế Lược Khúc Xạ (Regression Kink Design - RKD)	Phương pháp Biến Công cụ (IV) cho Suy luận Nhân quả
Lĩnh vực	Suy luận nhân quả	Kinh tế học y tế
Họ	Regression model	Process / pipeline
Năm ra đời	2015	1990s (modern applications)
Người khởi xướng	Card, Lee, Pei & Weber	Angrist & Pischke (applied econometrics); rooted in econometric theory
Loại	Quasi-experimental design (slope-based RDD)	Method
Công trình gốc	Card, D., Lee, D. S., Pei, Z. & Weber, A. (2015). Inference on Causal Effects in a Generalized Regression Kink Design. Econometrica, 83(6), 2453-2483.	Angrist, J. D., & Pischke, J. S. (2009). Mostly Harmless Econometrics: An Empiricist's Companion. Princeton: Princeton University Press.
Tên gọi khác	RKD, regression kink design, kink regression discontinuity, Regresyon Kırılma Tasarımı (RKD — Regression Kink Design)	IV, two-stage least squares, TSLS, causal estimation
Liên quan	4	3
Tóm tắt	The Regression Kink Design is a quasi-experimental method that estimates a causal effect when a policy rule creates a change in slope (a kink) — rather than a jump — at a known threshold of a running variable. It was formalised as a generalized design by Card, Lee, Pei and Weber (2015) and is the slope-based counterpart of the regression discontinuity design.	Instrumental variables (IV) is an econometric method to estimate causal effects when treatment or exposure is not randomly assigned and confounding is severe or unmeasured. IV relies on a third variable (instrument) that influences treatment but does not directly affect the outcome, allowing researchers to isolate the causal effect from the noise of confounding. Developed extensively in econometrics (Angrist & Pischke, 1990s–2000s), IV methods are increasingly used in health economics and health services research to leverage natural experiments and policy changes.