with M. Kejriwal, Econometric Reviews, 32(8), 892-927, 2013. Determining whether per capita output can be characterized by a stochastic trend is complicated by the fact that infrequent breaks in trend can bias standard unit root tests towards non-rejection of the unit root hypothesis. The bulk of the existing literature has focused on the application of unit root tests allowing for structural breaks in the trend function under the trend stationary alternative but not under the unit root null. These tests, however, provide little information regarding the existence and number of trend breaks. Moreover, these tests su¤er from serious power and size distortions due to the asymmetric treatment of breaks under the null and alternative hypotheses. This paper estimates the number of breaks in trend employing procedures that are robust to the unit root/stationarity properties of the data. Our analysis of the per-capita GDP for OECD countries thereby permits a robust classi cation of countries according to the growth shift, level shift and linear trend hypotheses. In contrast to the extant literature, unit root tests conditional on the presence or absence of breaks do not provide evidence against the unit root hypothesis.
with D.H. Papell, Journal of International Money and Finance, 31(6), 1440-1458, 2012. We study the behavior of inflation rates among the 12 initial Euro countries in order to test whether and when the group convergence initially dictated by the Maastricht treaty and now by the ECB, occurs. We also assess the impact of events such as the advent of the Euro and the 2008 financial crisis. Due to the small size of the estimation sample, we propose a new procedure that increases the power of panel unit root tests when used to study group-wise convergence. Applying this new procedure to Euro area inflation, we find strong and lasting evidence of convergence among the inflation rates soon after the implementation of the Maastricht treaty and a dramatic decrease in the persistence of the differential after the occurrence of the single currency. After the 2008 crisis, Euro area inflation rates follow the ECB’s price stability benchmark, although Greece reports relatively higher inflation.
Economics Bulletin, 29(1), 238-243, 2009. This study investigates the stationary behavior of the in¿ation rates for the Euro-zone members and some neighboring countries, for the 1957:2 to 2007:3 period. The analysis uses univariate unit root tests with enhanced small-sample performances that allow up to two breaks in the intercept, namely those of Elliott et al. (1996) and Lopez (2008). The results strongly reject the unit root null hypothesis for all the countries. Furthermore, they demonstrate that some of the Euro-zone inflation rates are stationary and others are regime-wise stationary. While such results may reconcile some of the literature findings and provide empirical evidence that the Maastricht criterion is respected, they also highlight the importance of accounting for breaks when studying these series
With J.F. Hoarau and M. Paul, Economics Bulletin, 30 (3):2321-29, 2010 This article analyzes the hysteresis hypothesis in the unemployment rates of the four “French overseas regions” (Guadeloupe, Martinique, Guyana, Reunion) [FORs] over the period 1993-2008. We use standard univariate and panel unit root tests, among them Choi (2006) and Lopez (2009) that account for cross-sectional dependence and have improved performance when the number of countries and the time dimension of the data are limited. Our results cannot reject the null hypothesis of a unit root and so find evidence supporting hysteresis in the unemployment rates for the FORs.
with J. Reyes, Applied Economics, 41(13), 1643 – 1651, 2009 Many economic theories connecting the real interest rate and the per-capita consumption growth rate require that both rates evolve together over time. This paper investigates whether these rates present similar stationary behavior for the seven most industrialized countries over the 1957-2005 period. The analysis relies on the unit root tests developed by Elliott, Rothenberg and Stock (1996) and Lopez (2006) to look for stationary or regime-wise stationary behavior, respectively. Furthermore, the final break selection uses Bai and Perron’s (2003) method. The results show for all the countries considered that both rates are either stationary or regime-wise stationary with a same number of breaks and, mostly, corresponding dates. The results hold whether the rates are calculated annually or quarterly.