Process and product R&D by a multiproduct monopolist

It is shown that the claim in Lambertini that a multiproduct monopolist's incentive for process R&D declines with the number of products it offers is incorrect. This incentive is in fact an increasing function of the number of products in his model. I further extend the model of Lambertini to show that whether or not process R&D incentive and the number of varieties are positively related depends on the degree of scope economies in process R&D. Product innovation promotes process R&D if the degree of such scope economies is high (as in Lambertini), and discourages it if the degree of scope economies is low. Copyright 2004, Oxford University Press.