PANEL UNIT ROOT TESTS WITH CROSS-SECTION DEPENDENCE: A FURTHER INVESTIGATION

2009 ◽  
Vol 26 (4) ◽  
pp. 1088-1114 ◽  
Author(s):  
Jushan Bai ◽  
Serena Ng

An effective way to control for cross-section correlation when conducting a panel unit root test is to remove the common factors from the data. However, there remain many ways to use the defactored residuals to construct a test. In this paper, we use the panel analysis of nonstationarity in idiosyncratic and common components (PANIC) residuals to form two new tests. One estimates the pooled autoregressive coefficient, and one simply uses a sample moment. We establish their large-sample properties using a joint limit theory. We find that when the pooled autoregressive root is estimated using data detrended by least squares, the tests have no power. This result holds regardless of how the data are defactored. All PANIC-based pooled tests have nontrivial power because of the way the linear trend is removed.

Author(s):  
Gülçin Güreşçi Pehlivan ◽  
Esra Ballı ◽  
Muammer Tekeoğlu

The Purchasing Power Parity suggests that differences in relative prices in two countries move together with nominal exchange rates in the long run. This study examines the validity of PPP as transition economies for Commonwealth of Independent States (CIS). Purchasing Power Parity holds only when the real exchange rate is stationary in the equation. To test the stationary, we used both time series and panel data analysis. Testing unit root both with time series and panel data in this study, provides us double check of the results. We also test the cross sectional dependence to choose the appropriate panel unit root test. Our test statistics indicate that there is cross section dependence between countries. Hence, one needs to take into consideration the cross section dependence while undertaking unit root tests. Otherwise, the results would be biased. ADF and KPPS indicate that PPP cannot be accepted for the countries except for Russia. According to the panel unit root test results indicate that PPP does not hold for Armenia, Belarus, Georgia, Kazakhstan and Kyrgyzstan except for Russia.


2019 ◽  
Vol 24 (3) ◽  
Author(s):  
Abdul Aziz Ali ◽  
Kristofer Månsson ◽  
Ghazi Shukur

AbstractIn this paper, we suggest a unit root test for a system of equations using a spectral variance decomposition method based on the Maximal Overlap Discrete Wavelet Transform. We obtain the limiting distribution of the test statistic and study its small sample properties using Monte Carlo simulations. We find that, for multiple time series of small lengths, the wavelet-based method is robust to size distortions in the presence of cross-sectional dependence. The wavelet-based test is also more powerful than the Cross-sectionally Augmented Im et al. unit root test (Pesaran, M. H. 2007. “A Simple Panel Unit Root Test in the Presence of Cross-section Dependence.” Journal of Applied Econometrics 22 (2): 265–312.) for time series with between 20 and 100 observations, using systems of 5 and 10 equations. We demonstrate the usefulness of the test through an application on evaluating the Purchasing Power Parity theory for the Group of 7 countries and find support for the theory, whereas the test by Pesaran (Pesaran, M. H. 2007. “A Simple Panel Unit Root Test in the Presence of Cross-section Dependence.” Journal of Applied Econometrics 22 (2): 265–312.) finds no such support.


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