We use a vertical product differentiation model under partial market coverage to study the social welfare optimum and duopoly equilibrium when convex costs of quality provision are either fixed or variable in terms of production. We show the following new results. First, under fixed costs, the...

In the first essay, I analyze a symmetric duopolistic market where each firm's choice regarding certain quality attributes such as the environmental friendliness of its product is its own private information. I find that the extent of horizontal differentiation between firms plays a crucial role...