We model how R&D enters the innovation system in four ways (intramural, extramural, cooperative, and spillover). Despite measuring three different spillovers together, for a very large sample of European enterprises we conclude that the productivity effects of spillovers were at best smaller...

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...