Convergence in international output: evidence from panel data unit root tests

This paper investigates international output convergence using methods of panel data unit root testing advocated by Im et al. (1997) and Breuer et al. (1999). Using quarterly data for a sample of OECD economies for the period 1960-98 on GDP differentials, the evidence suggests that power deficiency may be an issue where univariate ADF unit root tests find against convergence with respect to the US or Germany. However, while the Im et al. t-bar test offers strong evidence in favor of convergence, the Breuer et al. SURADF test suggests that this finding may in fact be driven by the rejection of non-stationarity in a small number of cases.