Σύγκριση μεθόδων

	Μοντέλο Πάνελ Σταθερών Επιδράσεων	Μέθοδος Εργαλειακών Μεταβλητών (IV) για Αιτιώδη Συμπερασματολογία
Πεδίο	Οικονομετρία	Οικονομικά της Υγείας
Οικογένεια	Regression model	Process / pipeline
Έτος προέλευσης	2005	1990s (modern applications)
Δημιουργός	Baltagi (textbook treatment); Hausman test for FE vs RE choice	Angrist & Pischke (applied econometrics); rooted in econometric theory
Τύπος	Panel data regression	Method
Θεμελιώδης πηγή	Hausman, J. A. (1978). Specification Tests in Econometrics. Econometrica, 46(6), 1251–1271.	Angrist, J. D., & Pischke, J. S. (2009). Mostly Harmless Econometrics: An Empiricist's Companion. Princeton: Princeton University Press.
Εναλλακτικές ονομασίες	within estimator, panel fixed effects, entity fixed effects model, Panel Sabit Etkiler Modeli	IV, two-stage least squares, TSLS, causal estimation
Συναφείς	5	3
Σύνοψη	The fixed effects panel model estimates relationships in panel data (many units observed over time) by exploiting only the within-unit variation, so that unobserved time-invariant heterogeneity is controlled away. It is the central within estimator developed in Baltagi's Econometric Analysis of Panel Data (2005), and the choice between it and the random effects model is settled by the Hausman (1978) test.	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.