قارن الطرق

	اختبار جذر الوحدة الأمثل نقطيًا لـ ERS	اختبار جذر الوحدة فيليبس-بيرون (PP)
المجال	الاقتصاد القياسي	الاقتصاد القياسي
العائلة	Hypothesis test	Regression model
سنة النشأة	1996	1988
صاحب الطريقة	Elliott, Rothenberg & Stock	Peter C. B. Phillips & Pierre Perron
النوع	One-sided parametric unit-root test	Unit-root test for stationarity
المصدر التأسيسي	Elliott, G., Rothenberg, T. J., & Stock, J. H. (1996). Efficient tests for an autoregressive unit root. Econometrica, 64(4), 813–836.	Phillips, P. C. B., & Perron, P. (1988). Testing for a unit root in time series regression. Biometrika, 75(2), 335–346.
الأسماء البديلة	ERS P-test, Point-Optimal Unit-Root Test, ERS PT statistic, ERS Nokta-Optimal Birim Kök Testi	PP test, Phillips-Perron unit root test, Phillips-Perron birim kök testi
ذات صلة	3	4
الملخص	The Elliott-Rothenberg-Stock (ERS) Point-Optimal test, introduced in their landmark 1996 Econometrica paper, is a near-efficient parametric procedure for testing whether a univariate time series contains a unit root. By first applying GLS detrending at a carefully chosen local-to-unity value and then computing a likelihood-ratio-type statistic, it achieves power close to the Gaussian power envelope—making it one of the most powerful unit-root tests available to applied econometricians.	The Phillips-Perron test, proposed by Peter Phillips and Pierre Perron in 1988, tests for a unit root in a time series, like the Augmented Dickey-Fuller test, but corrects for autocorrelation and heteroskedasticity in the errors non-parametrically rather than by adding lagged differences. It runs a simple Dickey-Fuller regression and then adjusts the test statistic using a long-run variance estimate, so the practitioner need not choose a lag length for the regression itself.