This paper concerns the classification of biases in the set of produced varieties in a monopolistically competitive equilibrium in the natural oligopoly setting. That is, we analyze the relationship between the set of produced goods in equilibrium when fixed costs are small and the set of produced goods by a social planner when fixed costs equal zero. It is shown that if all of the goods are substitutes, there are never too few varieties, and there may be too many. Conversely, if the goods are all complementary, there are never too many, and there may be too few.

[This paper develops a general, competitive model of commodity differentiation. The structure analyzed is sufficiently rich to admit the basic structures of many of the common models of commodity differentiation as special cases. Thus, the model provides a unifying framework within which alternative formulations of strategic product choice can be compared. It is shown that competitive equilibria exist under only mild restrictions on the underlying economic structure and vary continuously with endowments. Finally, some results relevant to all models of commodity differentiation featuring price taking consumers are presented. The results are shown to point to some potentially important methodological restrictions.]

In this paper, the characteristics model of Lancaster is reconsidered. It is shown by example that equilibrium prices need not be linearly decomposable. It does follow that equilibrium prices must be a convex function of characteristics, however. Further, it is shown that this fact holds independent of the form of firm competition (e.g., perfect or monopolistic). Finally, the predictions of the theory are discussed in the context of two empirical examples.

The authors' aim in this paper is to exposit a convex model of equilibrium growth. The model has two features that distinguish it from most other work on the subject: first, the model is convex on the technological side and, second, fixed factors are explicitly included. Existence and characterization results are provided along with some preliminary analyses of taxation and international trade policies. It is shown that the long-run growth rate in per capita consumption depends, in the natural way, on the parameters describing tastes, technology, and policies. It is demonstrated that, in a free-trade equilibrium with taxation, national growth rates of consumption and output need not converge.

The authors study the problem of optimal taxation in three infinite-horizon, representative-agent endogenous growth models. The first model is a convex model in which physical and human capital are perfectly symmetric. The authors' second model incorporates elastic labor supply through a Lucas-style technology. Analysis of these two models points out the danger of assuming that government expenditures are exogenous. In their third model, the authors include government expenditures as a productive input in capital formation, showing that the limiting tax rate on capital is no longer zero. In numerical simulations, they find similar effects on growth and welfare in all three models.

V. V. Chari, Ravi Jagannathan, Larry Jones; Price Stability and Futures Trading in Commodities*, The Quarterly Journal of Economics, Volume 105, Issue 2, 1