Labor Differentiation and Agglomeration in General Equilibrium

The aim of this paper is to explore the structure of cities as a function of labor differentiation, gains to trade, a fixed cost for constructing the transportation network, a variable cost of commodity transport, and the commuting costs of consumers. Firms use different types of labor to produce different outputs. Locations of all agents are endogenous as are prices and quantities. To our knowledege, this is the first paper that applies smooth economy techniques to urban economics. Existence of equilibrium and its determinacy properties depend crucially on the relative numbers of outputs, types of labor and firms. More differentiated labor implies more equilibria. We provide tight lower bounds on labor differentiation for existence of equilibrium. If these sufficient conditions are satisfied, then generically there is a continuum of equilibria for given parameter values. Finally, an equilibrium allocation is not necessarily Pareto optimal in this model.city structure, heterogeneous labor, transportation network, general equilibrium

Labor differentiation and agglomeration in general equilibrium

The aim of this paper is to explore the structure of cities as a function of labor differentiation, gains to trade, a fixed cost for constructing the transportation network, a variable cost of commodity transport, and the commuting costs of consumers. Firms use different types of labor to produce different outputs. Locations of all agents are endogenous as are prices and quantities. This is among the first papers to apply smooth economy techniques to urban economics. Existence of equilibrium and its determinacy properties depend crucially on the relative numbers of outputs, types of labor and firms. More differentiated labor implies more equilibria. We provide tight lower bounds on labor differentiation for existence of equilibrium. If these sufficient conditions are satisfied, then generically there is a continuum of equilibria for given parameter values. Finally, an equilibrium allocation is not necessarily Pareto optimal in this model.city structure; heterogeneous labor; transportation network; general equilibrium

Spatial Externalities and Empirical Analysis: The Case of Italy

In the last ten years the space issue, i.e. the study of the role played by space in economic phenomena, has attracted a lot of interest from many economic fields. The combination of increasing returns, market imperfections, and trade costs creates forces that, together with factor endowments, determine the distribution of economic activities. The aim of this work is to estimate a model of economic geography, using a space-time panel data on Italian provinces, in order to both test the empirical relevance of this theory, and try to give a measure of the geographic extent of spatial externalities. Particular attention has been devoted to address rigorously those endogeneity issues that naturally arises when dealing with both structural models and spatial data. Our results are consistent with the hypothesis that product-market linkages actually influence the geographic concentration of economic activities and that their spread over space is, contrary to previous findings, not negligible. --Economic Geography,Spatial Externalities,Market Potential

Methodological and empirical challenges in modelling residential location choices

The modelling of residential locations is a key element in land use and transport planning. There are significant empirical and methodological challenges inherent in such modelling, however, despite recent advances both in the availability of spatial datasets and in computational and choice modelling techniques. One of the most important of these challenges concerns spatial aggregation. The housing market is characterised by the fact that it offers spatially and functionally heterogeneous products; as a result, if residential alternatives are represented as aggregated spatial units (as in conventional residential location models), the variability of dwelling attributes is lost, which may limit the predictive ability and policy sensitivity of the model. This thesis presents a modelling framework for residential location choice that addresses three key challenges: (i) the development of models at the dwelling-unit level, (ii) the treatment of spatial structure effects in such dwelling-unit level models, and (iii) problems associated with estimation in such modelling frameworks in the absence of disaggregated dwelling unit supply data. The proposed framework is applied to the residential location choice context in London. Another important challenge in the modelling of residential locations is the choice set formation problem. Most models of residential location choices have been developed based on the assumption that households consider all available alternatives when they are making location choices. Due the high search costs associated with the housing market, however, and the limited capacity of households to process information, the validity of this assumption has been an on-going debate among researchers. There have been some attempts in the literature to incorporate the cognitive capacities of households within discrete choice models of residential location: for instance, by modelling households’ choice sets exogenously based on simplifying assumptions regarding their spatial search behaviour (e.g., an anchor-based search strategy) and their characteristics. By undertaking an empirical comparison of alternative models within the context of residential location choice in the Greater London area this thesis investigates the feasibility and practicality of applying deterministic choice set formation approaches to capture the underlying search process of households. The thesis also investigates the uncertainty of choice sets in residential location choice modelling and proposes a simplified probabilistic choice set formation approach to model choice sets and choices simultaneously. The dwelling-level modelling framework proposed in this research is practice-ready and can be used to estimate residential location choice models at the level of dwelling units without requiring independent and disaggregated dwelling supply data. The empirical comparison of alternative exogenous choice set formation approaches provides a guideline for modellers and land use planners to avoid inappropriate choice set formation approaches in practice. Finally, the proposed simplified choice set formation model can be applied to model the behaviour of households in online real estate environments.Open Acces

Methodology for an integrated modelling of macro and microscopic processes in urban transport demand

The paper presents the theoretical formulation and the underlying assumptions for an activity-based approach of transport demand modelling. Starting with the definition of a time hierarchy of decision-making in the urban environment, rules are formulated that dictate the general hierarchic structure of individuals’ choices in the urban system. The temporal scale defines decisions for activities and their daily sequence, the geographical scale decisions associated to destination choice processes. We build activity plans (number and daily sequence of activities) from an empirical data set and calculate trip paths (time-spatial trajectories including transport modes and travel destinations) assuming consumers to maximize their utility in the decision-making process. First results of the translation of the theoretical model into a real-world application are shown for the city of Santiago, Chile

CAPTIVE SUPPLIES AND THE CASH MARKET PRICE: A SPATIAL MARKETS APPROACH

Exclusive contracts (often called “"captive supplies”") between processors and farmers are in increasingly important feature of modern agriculture. We study an interesting empirical regulatory occurring in markets that feature both contract and spot exchange: the spot price is inversely related to the incidence of contract use in the market. We use a spatial model and a noncooperative game approach to show that processors can use exclusive contracts to manipulate the spot price in certain situations. Captive supplies in these settings represent geographic buffers that reduce competition among processors. However, in markets where the spatial dimension is less important, captive supplies are ineffective as barriers to competition because firms have incentive to “"jump"” across a captive supply region to procure the farm product.Agribusiness,

Benefits of Spatial Regulation in a Multispecies System

Spatial heterogeneity in multispecies systems affects both ecological interactions and the composition of harvest. A bioeconomic model is used to analyze the nonselective harvest of two stocks with generalized ecological interaction and different persistent distributions across two spatial strata. Harvester response to aggregate effort controls is shown to partially dissipate rents relative to the case where the spatial distribution of effort can be specified. Numerical solutions for time paths of spatial (first-best) and aggregate (secondbest) input constraints indicate factors affecting their relative efficiency. In the scenarios studied, benefits of spatial specificity range from 0 to 15% of total net present value (NPV), depending upon the spatial correlation of stocks, their relative growth rates and prices, and the cost gradient across space. The benefits of spatial regulation are also heightened by the presence of ecological interaction, especially predator-prey dynamics.Bycatch, multispecies system, second-best regulation, spatial, Q20, Q22, Q28, Resource /Energy Economics and Policy,