Evaluating alternative price expectation models for multiproduct supply analysis

Neoclassical economic theory provides an important conceptual framework for the analysis of agricultural production. Theory provides little guidance, however, in the actual specification of empirical models. This paper applies an integrated approach for choosing between price expectation mechanisms in a multiple-equation model when the alternatives are non-nested. Nine alternative specifications of market price and policy information are developed. Price forecasting accuracy, non-nested tests of hypotheses, and out-of-sample predictive accuracy are examined for agricultural production in Iowa. The results call into question the reliability of using forecasting accuracy as the sole guide to selecting a price expectation proxy.     

2007年四川粮食市场价格走势预测

2006年,由于受粮食供求总量偏紧、粮食市场流通不畅及国际市场粮价攀升等因素的影响,市场粮油价格在去年11月中旬后出现了较大幅度的上涨,并缓慢延升到今年.     

Rainfall or price variability: what determines rangeland management decisions? A simulation-optimization approach to South African savannas

Savannas cover the greater part of Africa and Australia and almost half of South America and contribute to the livelihoods of more than 350 million people. With the intensification of land use during the second half of the 20th century, savannas have become increasingly degraded through bush encroachment as a consequence of increased grazing pressure. Research on rangeland dynamics, however, provides contradicting answers with regard to the causes and possible remedies of bush encroachment. In this article we present results from an application of a simulation-optimization model to the case of extensive rangeland management in South Africa. Our model differs from previous approaches in that it explicitly accounts for the influence of stochastic prices and rainfall on economically optimal management decisions. By showing the implications of neglecting price variation and stochasticity in rangeland models we provide new insights with regard to the determinants of bush encroachment and rangeland managers' economic return. We demonstrate that, in the case of South Africa, optimal rangeland management is likely to lead to bush encroachment that eventually makes livestock holding unprofitable. Yet, we identify the costs of fire management to be a limiting factor for managers to counteract bush encroachment and explore the impact of policy measures to reduce fire control costs on the ecological and economic sustainability of livestock holding.     

Marketing margins and price transmission on the Hungarian beef market

There is a wealth of literature on farm-retail price spread for different commodities and countries. However, research on price transmission and marketing margins in the transition economies is still limited. The paper analyses two specific aspects of transition: the larger probability of asymmetric price transmission and structural changes in the case of Hungarian beef chain. The article identifies the date of structural break applying the Gregory and Hansen procedure with recursively estimated breakpoints and ADF statistics. Exogeneity tests reveal the causality runs from producer to retail prices. Homogeneity is rejected, suggesting a mark-up pricing strategy. Price transmission analysis suggests that, despite the common belief, price transmission on the Hungarian beef meat market is symmetric on both long and short run.     

Food scares, market power and price transmission: the UK BSE crisis

This paper is concerned with the impact of food scares, principallythe BSE crisis in the UK, and focuses on price transmissionin vertically related markets. We show that if market powerhas an effect on the farm–retail margin, this determinesthe specification of the cointegrating relationship and thusprovides a test of market power. The results for the UK beefchain suggest that we cannot reject the importance of marketpower. The impact of the BSE crisis on farm prices is foundto be more than double that on retail prices, thus corroboratingpublic concerns regarding a differential impact of food scareson retailers and producers.     

当前粮食市场保供稳价形势及对策

当前粮食形势十分复杂,保供稳价压力巨大,值得高度重视和认真研究。一、当前粮食保供稳价形势（一）供需形势全球粮食产量、贸易量和库存连年减少,消费持续增加．区域分布不均衡。据联合国粮农组织（FAO）数据．2010／2011年度全球粮食产量22．16亿吨,同比下降2．1％：贸易量2．69亿吨,减少2．3％;库存量5．13亿吨,下降7．2％。     

南非海洋渔业资源保护及其借鉴意义

本文在对南非海洋渔业状况进行概述的基础上,重点介绍了南非在海洋渔业资源保护方面采取的行之有效的措施加强对海洋资源的动态调查评估;强化对捕捞业的监督和管理;加强对海岸带的管理.有鉴于此,就我国渔业资源保护,提出了提高公众保护意识、建立健全法治体系、加大资金投入等建议.     

African indigenous vegetable enterprises and market access for small-scale farmers in East Africa

African indigenous vegetables (AIVs) have been part of the food systems in sub-Saharan Africa for generations. The region is a natural habitat for more than 45,000 species of plants, of which about 1,000 can be eaten as green leafy or fruit vegetables that happen to be the mainstay of traditional diets. During the colonial era, adventurers and slavers sailing in Africa introduced exotic plants such as maize, cassava and beans and, later, commercial crops such as sugarcane, cocoa, coffee and cotton, which began contributing more to life. Farmers integrated these crops into their age-old livelihood strategies at the expense of traditional subsistence crops. AIVs were almost entirely neglected and considered ‘poor people's' plants. To reverse the trend, FARM-Africa and its partners reintroduced AIVs which are now forming part of families’ diets as well as becoming a source of income for smallholder farmers in Arumeru, Tanzania and Kiambu, Kenya. AIVs are robust and productive, and thus well suited to feeding the hungriest and most vulnerable sections of society.     

Globalizing Ethics: Social Technologies of Private Regulation and the South African Wine Industry

This paper discusses of some key issues arising from South African experience of the UK-based Ethical Trading Initiative's (ETI) pilot project in the monitoring of compliance codes of conduct for product sourcing. The paper argues that the experience of 'local stakeholder participation' in the ETI's pilot project in the South African wine industry raises serious questions about the appropriateness and efficacy of 'ethical sourcing' as a vehicle for creative global–local engagement. It explores key elements of the globalizing 'technologies of ethics' deployed by projects like the ETI, and argues that these may simply normalize and regularize power relations in trade between North and South. These limitations are particularly serious in light of the course of labour market restructuring in South Africa, which has reshaped agricultural employment in ways that limit the ability of employment standards to address real difficulties faced by agricultural workers. This does not render 'ethical sourcing' irrelevant, nor does it mean that it can be read as simply securing retailer interests. It does mean, however, that a key question facing 'Southern' organizations and their allies is how to increase the scope for engagement and contestation around the implementation of such initiatives.     

投机力量主导下的粮价波动:来自期货市场的实证研究

投机是期货市场的常态,也是期货市场赖以存在和发展的基础.当投机因素与供求关系耦合在一起时,通常会形成巨大的期货价格波动,对实体经济产生冲击,最近.一轮粮价波动即含有这样的因素.对此,本文以郑州小麦期货合约为例,进行了相应的实证研究,并提出若干建议.     

Measuring market power in the French Comte cheese market

A new empirical industrial organisation approach is used tomeasure seller market power in the French Comté cheesemarket, characterised by government-approved supply control.The estimation is performed on quarterly data at the wholesalestage over the period 1985–2005. Three different elasticityshifters are included in the demand specification, and the supplyequation accounts for the existence of the European dairy quotapolicy. The market power estimate is small and statisticallyinsignificant. Monopoly is clearly rejected. Results appearto be robust to the choice of functional form and suggest littleeffect of the supply control scheme on consumer prices.     

Intra-annual sheep price patterns and factors underlying price variations in the central highlands of Ethiopia

A sheep market survey was undertaken to determine the effects of certain animal and market characteristics on price and the pattern of sheep prices in relation to seasons. Nine key Ethiopian central highlands markets were surveyed for a period of one year in 1989. Each market was surveyed once a week on the main market day. Price, weight, sex, age, colour, condition score, breed type and buyer's purpose were recorded for all completed transactions as well as the numbers offered and sold on each market day. A total of 50062 cases were recorded. Three markets, each representing redistributive, intermediate and terminal markets, as identified by the distribution in buyer's purpose were chosen for further analysis. Considerable weekly price variation was evident in these markets. Prices were also seasonal with higher premiums paid during some religious festivals. Animal characteristics (weight, age, condition, sex, colour) as well as buyer's purpose and seasons were variably important in explaining variation in price among animals within weeks. Variations in the composition of these characteristics from week-to-wcek were among factors underlying changes in weekly mean prices. R² varied from 0.2659 to 0.3583 in the quadratic price per kg model and from 0.7822 to 0.8413 in the quadratic price per head model in the three markets. However, it was found that price per head was predicted equally well overall by estimated price per kg multiplied by actual weights and that because of wide variation in weights, both within and between weeks, price per kg is more useful market information.     

An Empirical Comparison of "Frisch" and "Time Series" Demand price Elasticities for individual Commodities

In a classical article in 1959, Ragnar Frisch [8] developed a procedure, which, under the assumption of want independence¹ and given commodity budget shares, income elasticities, and one own-price elasticity, allows one to calculate a complete matrix of own and cross price elasticities. Between broad commodity groups such an assumption (want independence) has becme increasingly accepted and in fact under the label of separability has formed the basis for a family of demand models that are increasingly used to estimate demand elasticities for broad commodity groups (the linear expenditure system, the Rotterdam model, etc.). At the individual commodity level however, the assumption of want independence seems less viable, e.g., the utility one derives from pork is in general not considered independent from one's consumption of beef. However, it has become increasingly common (and apparently acceptable) to find the Frisch methodology utilized to develop demand price elasticity estimates for individual agricultural commodities [4, 7, 17].