Faculty of Economics and Business Administration Publications Database

Effect of Neglected Deterministic Seasonality on Unit Root Tests

Demetrescu, Matei
Volume: 48
Number: 3
Pages: 385 - 402
Link External Source: Online Version
Year: 2007
Keywords: Neglected seasonal means; Dickey-Fuller test; KPSS test

Whenever deterministic seasonality is ignored, the distribution of the Dickey-Fuller test is shifted to the left, with lower dispersion at the same time. When accounting for serial correlation, the distortions become less predictable. A Monte Carlo study confirms that the (augmented) Dickey-Fuller test without seasonal dummies is oversized and has little power at the same time, due to the need of lag augmentation. The effect of neglecting seasonal deterministics on the KPSS test for stationarity depends on the way the long-run variance is estimated.