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Full-Text Articles in Social and Behavioral Sciences
Testing For A Unit Root In The Presence Of Deterministic Trends, Peter C.B. Phillips, Peter Schmidt
Testing For A Unit Root In The Presence Of Deterministic Trends, Peter C.B. Phillips, Peter Schmidt
Cowles Foundation Discussion Papers
This paper provides a new unit root test based on an alternative parameterization which has previously been considered by Bhargava (1986). This parameterization allows for trend under both the null and the alternative, without introducing any parameters that are irrelevant under either. This is not so in the Dickey-Fuller parameterizations. The new test is extracted from the score or LM principle under the assumption that the errors are iid N(0, sigma squared (epsilon)), but our asymptotics hold under more general assumptions about the errors. Two forms of the test (a coefficient test and at t-test) are derived.
Testing For A Unit Root By Generalized Least Squares Methods In The Time And Frequency Domains, In Choi, Peter C.B. Phillips
Testing For A Unit Root By Generalized Least Squares Methods In The Time And Frequency Domains, In Choi, Peter C.B. Phillips
Cowles Foundation Discussion Papers
New time and frequency domain tests for the presence of a unit root are developed. The tests are based on generalized least squares (GLS) methods in both the time and the frequency domains. For the time domain tests, moving average processes are assumed for the error terms on the autoregression. For the frequency domain tests, general assumptions are made which allow for stationary and weakly dependent error processes. The limiting distributions of feasible GLS tests are derived under MA(1) errors in the time domain. This theory is extended to higher order moving average processes under an invertibility condition. The limiting …