This paper updates and extends the work of Barro (2000). International data confirm the presence of the Kuznets curve-an inverse-U shape relationship between income inequality and per capita GDP-that is relatively stable from the 1960s into the 2000s. The direct effect of international openness...

Noting that many economic variables display occasional shifts in their second order moments, we investigate the performance of homogenous panel unit root tests in the presence of permanent volatility shifts. It is shown that in this case, panel unit root tests derived under time invariant...