Convergence in income inequality? evidence from panel unit root tests with structural breaks

This paper empirically tests whether there is evidence of convergence in income inequality, as predicted by several versions of the neoclassical growth model, using a large panel of annual data for the 48 contiguous states in the US over the 1916–2005 period. By implementing the panel LM unit root test developed by Im et al. (Oxford Bull Econ Stat 67:393–419, 2005, Panel LM unit-root tests with trend shifts, Mimeo, 2010) that allows for the presence of structural breaks and heterogeneity in the panel, we find overwhelming evidence in support of convergence in income inequality. In addition, the results are robust to alternative inequality indicators used, different notions of stochastic convergence defined, and additional cross-sectional correlation considered.