Most communication services have a demand "externality" in that the benefit to a subscriber depends upon how many of his communication partners also subscribe. This article develops an economic model that determines both the required critical mass size for startup and the ultimate expansion...

When a good or service is offered in a variety of qualities with corresponding marginal prices, a quality-based allocation of consumption units by buyers is induced. This enables a monopolist supplier to achieve partial discrimination among buyers with different consumption preferences. We...