Firms selling multiple quality-differentiated products frequently alter their product lines when a competitor enters the market. We present a model of multiproduct monopoly and duopoly using a general `upgrades` approach that yields a powerful analytical framework. We provide a simple...

The single crossing property plays a crucial role in monotone comparative statics (Milgrom and Shannon (1994)), yet in some important applications the property cannot be directly assumed or easily derived.  Difficulties often arise because the property cannot be aggregated: the sum of two...

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Switching costs and network effects bind customers to vendors if products are incompatible, locking customers or even markets in to early choices. Lock-in hinders customers from changing suppliers in response to (predictable or unpredictable) changes in efficiency, and gives vendors lucrative ex...

The regulator of a natural monopoly that sets a two-part tariff and whose marginal cost is stochastic will generally want the price to vary less than marginal cost when the lump-sum charge in the tariff is fixed. A trade-off exists between efficient pricing and an optimal allocation of risk....

The welfare and output effects of monopoly third-degree price discrimination are analyzed when inverse demand functions are parallel.  Welfare is higher with discrimination than with a uniform price when demand functions are derived from the logistic distribution, and from a more general class...

This paper studies a simultaneous-move infinite-horizon delegation game in which the principal of a durable goods monopoly entrusts pricing decisions to a manager who enjoys consuming her monetary rewards but dislikes production effort. The delegation contract allows for continual interference...

Sufficient conditions are developed for third-degree price discrimination by a monopolist serving all markets to reduce and raise social welfare.  Welfare falls if the demand function in the market whose price is higher with discrimination is at least as convex as that in the other market (at...

The welfare effects of third-degree price discrimination are analyzed when demand in one market is an additively shifted version of demand in the other market and both markets are served with uniform pricing. Social welfare is lower with discrimination if the slope of demand is log-concave or...

This paper uses convexity arguments to determine the effects of monopolistic third-degree price discrimination on total output and welfare. We focus on benchmark cases, including constant demand elasticities, with constant curvature of inverse demand σ. We show how the effects of price...