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Random walk and breaking trend in financial series: An econometric critique of unit root tests

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  • Rahman, Abdul
  • Saadi, Samir

Abstract

The present note sheds light on several pitfalls associated with unit root tests that are overlooked by a growing volume of literature in financial economics. Specifically, several studies have confused unit root tests with the Random Walk hypothesis. Unit root tests are not designed for such a task since they aim at investigating whether a time series is difference-stationary or trend-stationary and are not, therefore, predictability tests. Secondly, we emphasize some serious shortcomings associated with the widely used unit root test developed by Zivot and Andrews [Zivot, E. & Andrews, D.W.K. (1992). Further evidence on the great crash, the oil-price shock, and the unit-root hypothesis. Journal of Business and Economic Statistics, 10, 251-270.]. In particular, we stress that results from the Zivot-Andrews test are sensitive to the methods employed to calculate the critical values and to select the maxim lag k. Furthermore, Zivot-Andrews test imposes a one time structural break in a time series; however recent studies showed that not counting for other true structural breaks may bias the results and may cause a spurious rejection of the unit root null hypothesis. Finally, we support our arguments by an empirical example based on the findings of Narayan and Smyth [Narayan, K.P. & Smyth, R. (2004). Is South Korea's stock market efficient? Applied Economics Letters, 11, 707-710.] with regards to the efficiency of South Korean stock market. We show that contrary to what the authors claim, the KSE (KOSPI) price index is predictable, and hence the South Korean stock market is not informationally efficient.

Suggested Citation

  • Rahman, Abdul & Saadi, Samir, 2008. "Random walk and breaking trend in financial series: An econometric critique of unit root tests," Review of Financial Economics, Elsevier, vol. 17(3), pages 204-212, August.
  • Handle: RePEc:eee:revfin:v:17:y:2008:i:3:p:204-212
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    1. Barnett, William A. & Ronald Gallant, A. & Hinich, Melvin J. & Jungeilges, Jochen A. & Kaplan, Daniel T. & Jensen, Mark J., 1995. "Robustness of nonlinearity and chaos tests to measurement error, inference method, and sample size," Journal of Economic Behavior & Organization, Elsevier, vol. 27(2), pages 301-320, July.
    2. Murray, Christian J. & Nelson, Charles R., 2000. "The uncertain trend in U.S. GDP," Journal of Monetary Economics, Elsevier, vol. 46(1), pages 79-95, August.
    3. Opong, Kwaku K. & Mulholland, Gwyneth & Fox, Alan F. & Farahmand, Kambiz, 1999. "The behaviour of some UK equity indices: An application of Hurst and BDS tests1," Journal of Empirical Finance, Elsevier, vol. 6(3), pages 267-282, September.
    4. Paresh Kumar Narayan & Russell Smyth, 2004. "Is South Korea's stock market efficient?," Applied Economics Letters, Taylor & Francis Journals, vol. 11(11), pages 707-710.
    5. Chaudhuri, Kausik & Wu, Yangru, 2003. "Random walk versus breaking trend in stock prices: Evidence from emerging markets," Journal of Banking & Finance, Elsevier, vol. 27(4), pages 575-592, April.
    6. David G. McMillan, 2003. "Non-linear Predictability of UK Stock Market Returns," Oxford Bulletin of Economics and Statistics, Department of Economics, University of Oxford, vol. 65(5), pages 557-573, December.
    7. Dickey, David A & Fuller, Wayne A, 1981. "Likelihood Ratio Statistics for Autoregressive Time Series with a Unit Root," Econometrica, Econometric Society, vol. 49(4), pages 1057-1072, June.
    8. Abhyankar, A & Copeland, L S & Wong, W, 1997. "Uncovering Nonlinear Structure in Real-Time Stock-Market Indexes: The S&P 500, the DAX, the Nikkei 225, and the FTSE-100," Journal of Business & Economic Statistics, American Statistical Association, vol. 15(1), pages 1-14, January.
    9. Zivot, Eric & Andrews, Donald W K, 2002. "Further Evidence on the Great Crash, the Oil-Price Shock, and the Unit-Root Hypothesis," Journal of Business & Economic Statistics, American Statistical Association, vol. 20(1), pages 25-44, January.
    10. Robin L. Lumsdaine & David H. Papell, 1997. "Multiple Trend Breaks And The Unit-Root Hypothesis," The Review of Economics and Statistics, MIT Press, vol. 79(2), pages 212-218, May.
    11. Lutz Kilian & Lee E. Ohanian, 1998. "Is there a trend break in U.S. GNP? A macroeconomic perspective," Staff Report 244, Federal Reserve Bank of Minneapolis.
    12. Perron, Pierre, 1989. "The Great Crash, the Oil Price Shock, and the Unit Root Hypothesis," Econometrica, Econometric Society, vol. 57(6), pages 1361-1401, November.
    13. Cheung, Yin-Wong & Chinn, Menzie D, 1997. "Further Investigation of the Uncertain Unit Root in GNP," Journal of Business & Economic Statistics, American Statistical Association, vol. 15(1), pages 68-73, January.
    14. Sophie Robé & Reinhold Kosfeld, 2001. "Testing for nonlinearities in German bank stock returns," Empirical Economics, Springer, vol. 26(3), pages 581-597.
    15. Kim, Tae-Hwan & Leybourne, Stephen J & Newbold, Paul, 2000. " Spurious Rejections by Perron Tests in the Presence of a Break," Oxford Bulletin of Economics and Statistics, Department of Economics, University of Oxford, vol. 62(3), pages 433-444, July.
    16. Ben-David, Dan & Papell, David H., 1995. "The great wars, the great crash, and steady state growth: Some new evidence about an old stylized fact," Journal of Monetary Economics, Elsevier, vol. 36(3), pages 453-475, December.
    17. McMillan, David G., 2005. "Non-linear dynamics in international stock market returns," Review of Financial Economics, Elsevier, vol. 14(1), pages 81-91.
    18. Diebold, Francis X & Senhadji, Abdelhak S, 1996. "The Uncertain Unit Root in Real GNP: Comment," American Economic Review, American Economic Association, vol. 86(5), pages 1291-1298, December.
    19. Balke, Nathan S. & Fomby, Thomas B., 1991. "Shifting trends, segmented trends, and infrequent permanent shocks," Journal of Monetary Economics, Elsevier, vol. 28(1), pages 61-85, August.
    20. Serletis, Apostolos & Shahmoradi, Asghar, 2004. "ABSENCE OF CHAOS AND 1/f SPECTRA, BUT EVIDENCE OF TAR NONLINEARITIES, IN THE CANADIAN EXCHANGE RATE," Macroeconomic Dynamics, Cambridge University Press, vol. 8(04), pages 543-551, September.
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    Cited by:

    1. Shyh-wei Chen, 2009. "Random walks in asian foreign exchange markets:evidence from new multiple variance ratio tests," Economics Bulletin, AccessEcon, vol. 29(2), pages 1296-1307.
    2. Chen, Shyh-Wei & Lin, Shih-Mo, 2014. "Non-linear dynamics in international resource markets: Evidence from regime switching approach," Research in International Business and Finance, Elsevier, vol. 30(C), pages 233-247.
    3. Juan Benjamín Duarte Duarte & Juan Manuel Mascare?nas Pérez-Iñigo, 2014. "Comprobación de la eficiencia débil en los principales mercados financieros latinoamericanos," ESTUDIOS GERENCIALES, UNIVERSIDAD ICESI, November.
    4. Antonio E. Noriega & Daniel Ventosa-Santaulària, 2010. "Spurious Long-Horizon Regression in Econometrics," Working Papers 2010-06, Banco de México.
    5. Abullah M. Noman & Minhaz U. Ahmed, 2008. "Efficiency of the foreign exchange markets in South Asian Countries," AIUB Bus Econ Working Paper Series AIUB-BUS-ECON-2008-18, American International University-Bangladesh (AIUB), Office of Research and Publications (ORP), revised Jun 2008.
    6. repec:eee:asieco:v:50:y:2017:i:c:p:62-72 is not listed on IDEAS
    7. Ventosa-Santaulària, Daniel & Noriega, Antonio E., 2015. "Long-run monetary neutrality under stochastic and deterministic trends," Economic Modelling, Elsevier, vol. 47(C), pages 372-382.
    8. Suresh K. G. & Aviral Kumar Tiwari & Anto Joseph, 2012. "Are the emerging bric stock markets efficient?," Economics Bulletin, AccessEcon, vol. 32(2), pages 1261-1271.

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