In this paper we present a unit root test against a nonlinear dynamic heterogenous panel with each cross section modelled as an LSTAR model. All parameters are viewed as cross section specific. We allow for serially correlated residuals over time and heterogenous variance among cross sections....

Utilizing panel data for 19 OECD countries we find suppor t for the hypothesis that a greater degree of product variety relative to the US helps to explain relative per capita GDP levels. The empirical work relies upon some direct measures of product variety calculated from 6-digit OECD export...