Tests for Unit Roots

A Monte Carlo Investigation


G. William Schwert

University of Rochester, Rochester, NY 14627
and National Bureau of Economic Research


Journal of Business and Economic Statistics, 7 (April 1989) 147-159
Reprinted as the lead article in the special 20th JBES Anniversary collection of influential papers.


Recent work by Said and Dickey [1984,1985], Phillips [1987], and Phillips and Perron [1988] examines tests for unit roots in the autoregressive part of mixed autoregressive-integrated-moving average (ARIMA) models (tests for stationarity). Monte Carlo experiments show that these unit root tests have different finite sample distributions than the unit root tests developed by Fuller [1976] and Dickey and Fuller [1979,1981] for autoregressive processes. In particular, the tests developed by Phillips [1987] and Phillips and Perron [1988] seem more sensitive to model misspecification than the high order autoregressive approximation suggested by Said and Dickey [1984].

Key words: Stationarity, ARIMA, Autoregressive, Moving average, Size

JEL Classifications: C22


Cited 506 times in the SSCI and SCOPUS through 2014
© Copyright 1989, American Statistical Association
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