Birgit Grodal

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We analyze the equilibrium size of networks under alternative market structures. Networks are characterized by positive size externalities (commonly called "network externalities"). That is, the benefits of the addition of an extra node (or an extra customer) exceed the private benefits accruing to the particular node (or customer). A direct consequence of(More)
We consider economies with incomplete markets, production, and a given distribution of initial endowments. The main purpose of the paper is to present a robust example of an economy with only one firm and one good per state in which no production decision entails a constrained efficient outcome. In particular, the unique Drèze equilibrium is dominated by(More)
This paper provides an extension of general equilibrium theory that incorporates the actions of individuals both as demanders and suppliers of goods and as members of firms, schools, social groups, and contractual relationships. The central notion of the paper is a group: a collection of individuals associated with one another for some purpose. The model(More)
In this paper we consider a model of group formation where group of individuals may have different feasible sets. We focus on two polar cases, increasing returns, when the set of feasible alternatives increases if a new member joins the group, and decreasing returns, when a new member has an opposite effect and reduces the number of alternatives available(More)
We consider a firm acting strategically on behalf of its shareholders. The price normalization problem arising in general equilibrium models of imperfect competition can be overcome by using the concept of real wealth maximization. This concept is based on shareholders’ aggregate demand and does not involve any utility comparisons. We explore the efficiency(More)
Collective consumption decisions taken by the members of a household may prove inefficient. The impact of such inefficient household decisions on market performance is investigated. At one extreme, market efficiency can occur even when household decisions are inefficient, namely when household inefficiencies are merely due to inefficient net trades with the(More)
We analyze the equilibrium size of networks under alternative market structures. Networks are characterized by positive size externalities (commonly called "network externalities"). That is, the benefits of the addition of an extra node (or an extra customer) exceed the private benefits accruing to the particular node (or customer). A direct consequence of(More)
This paper provides an extension of general equilibrium theory that incorporates the actions of individuals both as demanders and suppliers of goods and as members of ...rms, schools, social groups, and contractual relationships. The central notion of the paper is a group: a collection of individuals associated with one another for some purpose. The model(More)