The authors examine the timing and quality of product introduction in an R&D stopping game, where they allow for horizontal and vertical differentiation in the product market. They observe that discontinuous changes in introduction dates can occur as firms' abilities as researchers change....

We examine the timing and quality of product introduction in an R&D stopping game, where we allow for horizontal and vertical differentiation in the product market. We observe that discontinuous changes in introduction dates can occur as firms' abilities as researchers change. Further, when the...

In the third essay I show that the existence of homogeneous products in a market depends on choices made by firms. If search costs are small or the proportion of consumers who search costlessly (shoppers) is large, firms have incentives to differentiate themselves vertically. On the other hand,...