Methoden vergelijken

	Tijdsvariërende parameter PP unit root test	Zivot-Andrews eenheidsworteltest met één structurele breuk
Vakgebied	Econometrie	Econometrie
Familie	Regression model	Hypothesis test
Jaar van ontstaan	1988-1999	1992
Grondlegger	Extension of Phillips & Perron (1988); TVP framework attributed to Hall & Luginbuhl (1999) and related literature	Eric Zivot & Donald Andrews
Type	Unit root test with time-varying parameters	Sequential unit-root test with endogenous break-point selection
Oorspronkelijke bron	Phillips, P. C. B., & Perron, P. (1988). Testing for a unit root in time series regression. Biometrika, 75(2), 335-346.	Zivot, E., & Andrews, D. W. K. (1992). Further evidence on the great crash, the oil-price shock, and the unit-root hypothesis. Journal of Business & Economic Statistics, 10(3), 251–270.
Aliassen	TVP-PP unit root test, time-varying PP test, Phillips-Perron test with time-varying parameters, TVP unit root test	ZA Test, Zivot-Andrews Break Test, Endogenous Break Unit-Root Test, Zivot-Andrews Birim Kök Testi
Verwant	3	3
Samenvatting	The time-varying parameter PP unit root test extends the classical Phillips-Perron test by allowing the autoregressive coefficient to change over time. It detects stochastic non-stationarity in series whose persistence may shift across regimes or periods, offering more reliable inference when structural change is suspected in the data-generating process.	The Zivot-Andrews (ZA) test, introduced by Eric Zivot and Donald Andrews in 1992, is a sequential unit-root test that allows for a single structural break at an unknown date. It extends the augmented Dickey-Fuller framework by endogenously selecting the break point that provides the strongest evidence against the unit-root null hypothesis, making it particularly useful for macroeconomic and financial time series that may have been disrupted by events such as policy changes, financial crises, or supply shocks.