Time-series regressions including non-linear transformations of an integrated variable are not uncommon in various fields of economics. In particular, within the Environmental Kuznets Curve (EKC) literature, where the effect on the environment of income levels is investigated, it is standard...

Time-series regressions including non-linear transformations of an integrated variable are not uncommon in various fields of economics. In particular, within the Environmental Kuznets Curve (EKC) literature, where the effect on the environment of income levels is investigated, it is standard...

Properties of estimators of long-run parameters in a polynomial regression with nonstationary, strongly exogenous regressors are considered in the context of the Environmental Kuznets Curve using Monte Carlo simulations. Standard inferential procedures seem to work well in this context.