The question of how to properly model production systems with unintended outputs has proven both controversial and of particular interest to the productivity and efficiency community. The paper explains why some of the arguments put forward in these controversies are hardly convincing for...

The directional distance function (DDF) framework has been widely used to estimate the marginal abatement cost (MAC) of CO2 emissions to support decision-making in environmental sustainability and climate change issues. In the use of DDF, an important task is mapping evaluated entities towards a...

This article provides a generalization of the materials balance-based production model introduced by Coelli et al. (2007). Based on this, some new environmental efficiency (EE) measures are presented. The Coelli et al. (2007) EE measure and its extension by Rødseth (2016) produce biased...