השוואת שיטות

	מבחן DF-GLS: מבחן שורש יחידה של דיקי-פולר מנוטרל באמצעות GLS	מבחן ERS לשרשי יחידה אופטימלי-נקודתי	מבחן קיי.פי.אס.אס (KPSS) לנייחות
תחום	אקונומטריקה	אקונומטריקה	אקונומטריקה
משפחה	Hypothesis test	Hypothesis test	Regression model
שנת המקור	1996	1996	1992
הוגה השיטה	Elliott, Rothenberg & Stock	Elliott, Rothenberg & Stock	Kwiatkowski, Phillips, Schmidt & Shin
סוג	One-sided t-test on GLS-detrended series	One-sided parametric unit-root test	Stationarity test (reverse of unit-root tests)
מקור מכונן	Elliott, G., Rothenberg, T. J., & Stock, J. H. (1996). Efficient tests for an autoregressive unit root. Econometrica, 64(4), 813–836.	Elliott, G., Rothenberg, T. J., & Stock, J. H. (1996). Efficient tests for an autoregressive unit root. Econometrica, 64(4), 813–836.	Kwiatkowski, D., Phillips, P. C. B., Schmidt, P., & Shin, Y. (1992). Testing the null hypothesis of stationarity against the alternative of a unit root. Journal of Econometrics, 54(1–3), 159–178.
כינויים	Elliott-Rothenberg-Stock test, ERS unit-root test, GLS-detrended Dickey-Fuller test, DF-GLS birim kök testi	ERS P-test, Point-Optimal Unit-Root Test, ERS PT statistic, ERS Nokta-Optimal Birim Kök Testi	Kwiatkowski-Phillips-Schmidt-Shin test, stationarity test, KPSS durağanlık testi
קשורות	3	3	4
תקציר	The DF-GLS test, introduced by Elliott, Rothenberg, and Stock (1996), is a modified augmented Dickey-Fuller procedure that applies generalized least squares (GLS) detrending before the standard unit-root regression. By removing deterministic components under a local alternative rather than the null hypothesis, the test achieves near-optimal power for detecting stationarity in time series, making it the preferred unit-root test in applied econometrics when a trend or intercept is present.	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 KPSS test, introduced by Kwiatkowski, Phillips, Schmidt and Shin in 1992, tests the null hypothesis that a series is stationary against the alternative that it contains a unit root — the reverse of the ADF and Phillips-Perron tests. By flipping the burden of proof, it is designed to be used alongside unit-root tests so that the two can confirm one another and expose ambiguous, borderline cases.