According to Chang et al. (2013), social welfare under licensing is lower than under no-licensing if the R&D efficiency is high. We show that this result is not correct, as when R&D efficiency is high social welfare is higher under licensing than under no-licensing.

In linear-city models, if firms are allowed (not allowed) to locate outside the linear city, they engage in excessive (insufficient) R&D investments from the normative viewpoint. This implies that the feasible set of locations drastically affects their investments.