Markets and pro-poor agricultural growth: insights from livelihood and informal rural economy models in Malawi

This article presents the development of a set of programming models describing the major features of different rural livelihoods and of the informal rural economy they together make up in Malawi. The models allow for differentiated responses by different household types to change and for the partial equilibrium effects of consequent supply, demand, and price adjustments in labor and grain markets. The models provide insights into the relations between own‐farm and nonown‐farm activities in different households' livelihoods and in the informal rural economy as a whole, and are used to investigate possible impacts of increasing cash crop prices and of a more open rural economy. Impacts of these changes on the poor are found to be critically dependent upon supply and demand elasticities in labor and grain markets, but the poor could potentially suffer significant losses from increased openness of the local economy leading to increased expenditure by less poor households on imported goods and services.     

A consumer education programme based on the Transtheoretical Model of Change

MONEY 2000? is a successful consumer education programme that was implemented by Cooperative Extension personnel in over two dozen states of the USA between 1996 and 2002. One of the unique features of this programme is that it was based on the Transtheoretical Model of Change (TTM), a framework that has been widely used to study health‐related behaviour changes such as smoking cessation. This paper first describes how the MONEY 2000? programme was developed around major constructs contained within the TTM. Findings are reported from a survey conducted with participants in the first two states that delivered the programme. The findings suggest that several change processes used by MONEY 2000? participants are associated with specific stages of change. In addition, there may be differences in behavioural changes between participants who increased their savings and those who reduced their debts.     

Bounding the inefficiency of equilibria in nonatomic congestion games

Equilibria in noncooperative games are typically inefficient, as illustrated by the Prisoner's Dilemma. In this paper, we quantify this inefficiency by comparing the payoffs of equilibria to the payoffs of a “best possible” outcome. We study a nonatomic version of the congestion games defined by Rosenthal [Int. J. Game Theory 2 (1973) 65], and identify games in which equilibria are approximately optimal in the sense that no other outcome achieves a significantly larger total payoff to the players—games in which optimization by individuals approximately optimizes the social good, in spite of the lack of coordination between players. Our results extend previous work on traffic routing games.     

Global instability in experimental general equilibrium: the Scarf example

Scarf (Int. Econ. Rev. 1 (1960) 157) proposed a model of dynamic adjustment in which the standard tatonnement price adjustment process orbits around, rather than converges to, the competitive equilibrium. Hirota (Int. Econ. Rev. 22 (1981) 461) characterized the price paths. We explore the predictions of Scarf's model in a non-tatonnement experimental double auction. The average transaction prices in each period do follow the path predicted by the Scarf and Hirota models. When the model predicts convergence the data converge; when the model predicts orbits, the data orbit in the direction predicted by the model. Moreover, we observe a weak tendency for prices within a period to follow the path predicted by the model.     

预防液化石油气储罐应力腐蚀的初探

液化石油气储罐在工业和人民生活中有着广泛的应用,探讨液化石油气中所含H2S腐蚀介质对储罐的应力腐蚀及预防措施显得非常重要。     

CROSS‐DOCKING AND ITS IMPLICATIONS IN LOCATION‐DISTRIBUTION SYSTEMS

Cross‐docking replaces traditional warehousing, enabling continuous flow of items without storage. Here we model location‐distribution networks, that include cross‐docking facilities, to obtain the latter's impact on the supply chain. We formulate optimization models to minimize total cost in three multi‐echelon networks, each model generalizing the preceding one. The first includes a single manufacturer, one product type, and multiple customers. Cross‐docks are to be located between origin and destinations. Besides solving optimally, a tool for quantitative analysis of direct‐shipment decisions is developed. The second model considers more than one product: We determine a cost‐effective sequence of items for indirect shipment (via cross‐docks). Finally, in a network with multiple origins, optimal solutions are obtained for 40 medium‐sized and larger examples.     

THE SQUARED ORNSTEIN-UHLENBECK MARKET

We study a complete market containing J assets, each asset contributing to the production of a single commodity at a rate that is a solution to the squared Ornstein-Uhlenbeck (Cox-Ingersoll-Ross) SDE. The assets are owned by K agents with CRRA utility functions, who follow feasible consumption/investment regimes so as to maximize their expected time-additive utility from consumption. We compute the equilibrium for this economy and determine the state-price density process from market clearing. Reducing to a single (representative) agent, and exploiting the relation between the squared-OU and squared-Bessel SDEs, we obtain closed-form expressions for the values of bonds, assets, and options on the total asset value. Typical model parameters are estimated by fitting bond price data, and we use these parameters to price the assets and options numerically. Implications for the total asset price itself as a diffusion are discussed. We also estimate implied volatility surfaces for options and bond yields.     

Estimation of Agricultural Production Functfons on a World-Wide Basis

Agricultural production is becoming increasingly capital and research intensive. Hayami and Ruttan, along with others, have developed and applied the metaproduction functional approach to the examination of this phenomenon on a worldwide basis. Limitations to the approach derive from a restrictive functional form chosen for estimation, and from a restrictive specification of agricultural capital and land. This study addresses those difficulties by use of the flexible translog functional form for estimation and by specifying an overall agricultural capital index and a land measure incorporating differences in the quality of land (agricultural natural resource) endowments. Estimation results indicate that agricultural comparative advantage in production is likely shifting to developed countries relative to LDC's due to capital constraints in the latter. Also agricultural potential (i.e., land endowments) do not serve to differentiate nations on the basis of agricultural production. Investment in agriculture, including land improvement, is key to the determination of comparative advantage. La production agricole fait appelle de plus en plus a beaucoup de re-cherches et de capitaux. Hayami et Ruttan, avec d'autres, ont developpe et appliqué l'approche fonctionnelle métaproduction pour examiner ce phénomena à l‘échelle du monde. Les limitations de cette approache provienneent de la forme fonctionnelle restrictive choisie pour l'estimation, et de la spécification restrictive de capitaux et terres agricoles. Cette étude traite ces difficultés en utilisant la formule “translog’ fonctionnelle adaptable pour l'estimation et en spécificant un indice du capital agricole global et une mesure de terre qui incorpore les différences du qualité des terres agricoles (ressources agricoles naturelles). Tous les résultats estimatifs indiquent que l'avantage comparatif agricole de production s'incline vers les pays développés parraport aux PMD dû aux constraintes de capitaux dans ces derniers. Aussi la capacité agricole (c'est à dire la richesse des sols) ne sert pas à différencier les nations sur le plan de production agricole. L'investissement dans l'agriculte, notamment l'amélioration de terre, est la cief pour déterminer l'avantage comparatif.     

How to get firms to invest: A simple solution to the hold-up problem in regulation

Abstract. Many governmental programs are effective only if firms make costly investments. The inability of authorities to precommit to a regulatory scheme creates incentives for firms not to invest and to hold-up the regulator. This paper describes a simple subsidy/tax scheme embedded in a four-stage mechanism that solves the hold-up problem. We design a self-financing subsidy/tax scheme which benefits a complying firm at the expense of a non-complying firm. In order to be credible, the subsidy and tax rates must maximize social welfare for any combination of investment decisions. We show that there exists a unique subgame perfect equilibrium in which all firms invest and no actual implementation with subsidies and taxes is required. We discuss in which cases the mechanism can work under incomplete information. Received: 30 December 1998 / Accepted: 12 October 2001     

Symmetry and order in the portfolio allocation problem

Summary. This research studies the role of multivariate distribution structures on random asset returns in determining the optimal allocation vector for an expected utility maximizer. All our conclusions pertain for the set of risk averters. By carefully disturbing symmetry in the distribution of the, possibly covarying, returns, we ascertain the ordinal structure of the optimized allocation vector. Rank order of allocations is also established when a permutation symmetric random vector is mapped into the returns vector through location and scale shifts. It is shown that increased dispersion in the vectors of location and scale parameters benefit, ex-ante, investors as does a decrease in the rank correlation coefficient between the location and scale parameter vectors. Revealed preference comparative static results are identified for the location and scale vectors of asset returns. For most issues addressed, we arrive at much stronger inferences when a safe asset is available. Received: August 8, 2000; revised version: January 8, 2001