This paper proposes a conditional directional distance function model in order to examine the link between regional environmental efficiency and GDP per capita levels. As an illustrative example we apply our model to USA regional data revealing an inverted ‘U’ shape relationship between...

This paper by applying a directional distance function approach measures the UK regions’ municipality waste performance. In addition the paper constructs conditional stochastic kernels trying to determine nonparametrically the association of regions’ GDP per capita levels with their...

This paper, by using conditional directional distance functions as introduced by Simar and Vanhems [J. Econometrics 166 (2012) 342-354] modifies the model by Färe and Grosskopf [Eur. J. Operat. Res. 157 (2004) 242-245], examines the link between regional environmental efficiency and economic...