Σύγκριση μεθόδων

	Επεκτεταμένος Έλεγχος Ριζικής Μονάδας Phillips-Perron (PP) με Ανθεκτικότητα	Δοκιμή Phillips-Perron για Μοναδιαία Ρίζα
Πεδίο	Οικονομετρία	Οικονομετρία
Οικογένεια	Regression model	Regression model
Έτος προέλευσης	1988 (base); 2000s–2010s (robust extensions)	1988
Δημιουργός	Phillips & Perron (1988); robustification by Cavaliere & Taylor (2008) and related authors	Peter C. B. Phillips and Pierre Perron
Τύπος	Unit root / stationarity test	Hypothesis test (unit root)
Θεμελιώδης πηγή	Phillips, P. C. B., & Perron, P. (1988). Testing for a unit root in time series regression. Biometrika, 75(2), 335–346.	Phillips, P. C. B., & Perron, P. (1988). Testing for a unit root in time series regression. Biometrika, 75(2), 335–346.
Εναλλακτικές ονομασίες	robust Phillips-Perron test, heteroskedasticity-robust PP test, nonparametric robust unit root test, robust PP	PP test, PP unit root test, Phillips-Perron test, nonparametric unit root test
Συναφείς	6	5
Σύνοψη	The Robust Phillips-Perron unit root test extends the classical PP test by applying corrections — such as heteroskedasticity-consistent covariance estimation or wild-bootstrap critical values — that maintain valid inference when the error variance of a time series is non-constant or exhibits unconditional heteroskedasticity, conditions under which the standard PP test is severely size-distorted.	The Phillips-Perron (PP) test is a nonparametric unit root test for time series that corrects for serial correlation and heteroscedasticity in the error term without adding lagged differences. Introduced by Phillips and Perron (1988), it applies a kernel-based long-run variance estimator to adjust the Dickey-Fuller statistic, making it robust to a wide class of weakly dependent error processes.