Knowledge that Transforms

Humans exhibit a fundamental propensity to interact for social, cultural, technological, and other reasons. In this paper we seek to determine when the propensity to interact, expressed in the form of a spatial externality, becomes strong enough to induce agglomeration. We design an abstract world where the only possible reason for agglomeration is the spatial externality. In this world the uniform population distribution is a steady-state. Then to ask under what circumstances does a spatial externality induce agglomeration is to ask under what circumstances does it induce an instability of the steady-state: anything other than a uniform steady-state implies some agglomeration.

[This paper examines the effect of the capital gains tax on investors' optimal consumption and investment behavior and on equilibrium asset prices in an intertemporal economy. It explictly considers the fact that capital gains and losses on stock are taxed only when the investor sells the stock. Ownership of stock then confers upon the investor a timing option which enables him to realize capital losses immediately and defer capital gains. This option is a large fraction of the total benefit which accrues to the stockholder, and is the prime reason for the novel implications of capital gains taxation, discussed in this paper.]

Institutional and Behavioral Economics, Labor and Human Capital

[We discuss long-run properties of Leontief input-output systems that are subject to technical change. We derive a necessary and sufficient condition on changes in input coefficients for the economy to remain productive for all time. We define Harrod-neutral change in Leontief systems, and show that, under specified conditions, Harrod-neutral change increases output possibilities asymptotically as quickly as any alternative form of technical change.]

This paper examines the identifiability of the coefficients of a single equation in a simultaneous equation model which is nonlinear only in the variables. The concept of identifiability in this model is motivated and developed using the closely related concept of observational equivalence. This framework is then utilized to develop necessary and sufficient conditions for identifiability when the disturbances are required to be independent of the exogenous variables. The approach recommended by Fisher is shown to yield sufficient but not necessary conditions for identifiability. For several relatively common special cases the necessary and sufficient conditions are found to simplify to the familiar rank condition for identifiability in the linear model. THE SIMULTANEOUS EQUATION MODEL that is nonlinear only in the variables has enjoyed widespread application in economics. Such models are linear in the parameters and typically seem to be linear in the variables as well, when viewing a single equation. In many models the nonlinearity in the variables arises due to endogenous variables entering in different forms in different equations (logged and unlogged form, for example). In macroeconometric models nonlinearity in the variables arises when the model includes endogenous real, nominal, and price variables, which are nonlinearly related.2 Whatever the reason for the nonlinearity in the variables, it is important to determine the conditions under which the equations of such models can be identified.

[This paper explores the possibilities opened up by combining preference aggregation and randomization in passing from individual to collective judgements about alternatives. We study the distribution of power under functions which assign to each profile of individual preferences a probabilistic judgement on each pair of alternatives x, y, that is, a probability of x being considered socially at least as good as y. Conditions are described under which the power of coalitions to guarantee that an alternative is not declared worse than another is subadditive, while their power to guarantee that one alternative is not declared better than another is superadditive. These results extend some of the main findings on the structure of decisive coalitions under deterministic social choice rules.]

The notion of a club efficient allocation, introduced in this paper, is shown to allow for a unifying treatment of rather disparate matters. The main result deals with the dual characterization of such allocations. The fundamental theorems of welfare economics, the limit theorem on the core, and a general version of a Henry George Theorem on the relationship between aggregate land rent and local public expenditures, all can be recovered as special cases of this paper's main result.

The purpose of this article is to provide a deeper empirical insight into the structural change of an industry which is more relevant than that obtained by an analysis based on the traditionally estimated average production function. The main contribution is a long run analysis of technical progress and structural change by means of the short run industry production function introduced by Johansen [13], and based on micro data for individual production units. For that purpose we have developed Johansen’s approach into an operational framework for discrete capacity distributions including a special algorithm for the computation of the short-run industry production function. (This abstract was borrowed from another version of this item.)

Article plaidant en faveur de l'utilisation d'estimateurs d'equations simultanees pour estimer les modeles d'effets aleatoires dynamiques d'un panel de donnees

[A model is constructed in which a potential entrant uses prices to make inferences about industry conditions. Stochastic demand shocks occur after the incumbent firm's action, so that prices reveal only statistical information about the incumbent's private information. The equilibrium differs from standard signalling equilibria in that it can be unique, it depends on prior beliefs, and it is rich in comparative statics. Conditions are obtained for entry threats to result in limit pricing, lower entry probabilities, and lower expected profits for potential entrants.]