CFDP 1189

A Primer on Unit Root Testing


Publication Date: August 1998

Pages: 51


The immense literature and diversity of unit root tests can at times be confusing even to the specialist and presents a truly daunting prospect to the uninitiated. In consequence, much empirical work still makes use of the simplest testing procedures because it is unclear from the literature and from recent reviews which tests if any are superior. This paper presents a survey of unit root theory with an emphasis on testing principles and recent developments. The general framework adopted makes it possible to consider tests of stochastic trends against trend stationarity and trend breaks of a general type. The main tests are listed, and asymptotic distributions are given in a simple form that emphasizes commonalities in the theory. Some simulation results are reported, and an extensive list of references and an annotated bibliography are provided.


Autoregressive unit root; Brownian motion; Functional central limit theorem; Integrated process; LM principle; Model selection; Moving average unit root; Nonstationarity; Quasi-differencing; Stationarity; Stochastic trend

See CFP: 972