Symmetric Positive Equilibrium Problem: A Framework for Rationalizing Economic Behavior with Limited Information

The PMP methodology is extended to deal with many economic units, self-selection arising from heterogeneous economic behavior, and multiple limiting inputs. The novel structure for the analysis of this type of problems acquires the name symmetric positive equilibrium problem. This methodology is articulated in three phases that parallel those one of positive mathematical programming. The recovery of a cost function that calibrates the base-year decisions of each economic unit is realized within a maximum entropy framework. The methodology is illustrated by the analysis of a sample of Italian farms that operate under the complex policy mandates of the European Union.     

Recovering the Shadow Value of Nutrients

This article investigates the shadow values of twenty-eight different nutrients. It links the unit price of foods to the shadow values of nutrients by building on a utility theoretic model first proposed by Gorman. Maximum entropy principles are then used to reason consistently about the values of the parameters of interest. The resulting estimates are discussed and analyzed.     

Searching an Ex Situ Collection of Wheat Genetic Resources

A theoretical model is developed and applied to the search for disease and pest resistance in ex situ collections of wheat genetic resources, employing actual data on frequency distributions, disease losses, and search costs. Experiments developed from case studies clarify several misperceptions about the value of gene banks and their utilization by breeders. The observation that wheat breeders use gene banks rarely does not imply that marginal accessions have low value. High costs of transferring genes with conventional breeding techniques mean that it may be efficient to store certain categories of genetic resources (such as landraces) 'unused' for many years.     

对生态系统服务价值问题的思考

介绍了生态系统服务的内涵、评估生态系统服务价值的意义,论述了生态系统总经济价值的构成及其评估方法,得到生态系统总经济价值体现的各种不同状态,需要多种研究方法结合共同探讨其合适的保护政策的结论。     

Estimating Crop-Specific Production Technologies in Chinese Agriculture: A Generalized Maximum Entropy Approach

A generalized maximum entropy approach is adapted to empirically estimate crop-specific production technologies in Chinese agriculture. Despite a modest behavioral assumption about equal marginal returns of nonland inputs among crops, this method does not require price information, which is usually distorted in a centrally planned economy such as China. A multi-output technology for Chinese agriculture is estimated and input allocations for each province are recovered simultaneously. The estimated multi-output production technology and input allocations imply that China may have greater grain production potentials than previously thought.     

Estimating Price Elasticities of Food Trade Functions: How Relevant is the CES‐based Gravity Approach?

The main objective of this article is to examine econometric estimates of price elasticities of food trade functions. We investigate the relevance of the prominent gravity approach. This approach is based on the assumptions of symmetric, monotone, homothetic, Constant Elasticity of Substitution (CES) preferences. We test all these assumptions using intra‐European trade in cheese. In general, the assumptions made on preferences by the gravity approach are not supported by our dataset. The bias induced in the estimated price elasticities is ambiguous.     

Choosing Brands: Fresh Produce versus Other Products

Assuming that brands contribute to quality risk reduction, prestige, and design, we derive and test hypothesis on the willingness to pay (WTP) for brands across different product categories (electronics, clothing, packaged food, and fresh produce). Using the random effect tobit model on the stated point value of WTP and the ordered probit model on the stated range of WTP, we find that WTP for brands of fresh produce is least among the four product categories controlling for relevant demographic variations. Simulations show that fresh produce has a higher optimal price premium for brands but with a much smaller market share.     

Using stated preference techniques to value four key ecosystem services on New Zealand arable land

Many researchers have noted that not only natural ecosystems but also landscapes actively modified by humans (engineered or designed ecosystems) can significantly impact the level of ecosystem goods and availability of services, thereby impacting human and social welfare. In New Zealand, agricultural lands are the largest area of engineered ecosystems on the national landscape. Study of the welfare effects of ecosystem services delivered by agricultural land can provide important insights into the management of engineered or designed ecosystems. This paper uses the contingent valuation method (CVM) and choice modelling to estimate values of four key ecosystem services: climate regulation, water regulation, soil retention and scenic views, for New Zealand land used for arable farming.     

Building an empirically-based framework to value multiple public goods of agriculture at broad supranational scales

Agricultural landscapes deliver multiple, highly valued goods such as cultural amenities, biodiversity conservation and climate stability. These goods are often delivered as side-effects of farmers' production decisions driven by broad-scale, supranational changes in agricultural, trade or other policies. Human well-being is thus affected in ways not taken into account in these macro-policy decisions. To avoid this policy failure, there is a growing demand for the valuation of broad-scale changes in public goods by the general public. For this purpose, context-rich valuation scenarios at this broad scale need to be developed which are empirically-based, policy-relevant and understandable by the general public. In this way, respondents are focused on actual trade-offs rather than invited to give symbolic reactions. This paper presents and discusses a valuation framework developed to fulfil these criteria. The approach is based on a typology of Macro-Regional Agri-Environmental Problems (MRAEP). Each MRAEP is defined by: (1) prevailing farming systems and agricultural landscapes; (2) current levels of public-good delivery; (3) expected direction of land-use change; and (4) expected effects of such change on public-good provision in each macro-region. Multivariate analysis of EU-wide data on agricultural landscapes and farming-systems led to identify thirteen macro-regions in the EU. Current public-good provision was described using public-good indicators. Only those public goods that are expected to change or could be improved by available policy options (core public goods) were used to generate choice alternatives for survey respondents. The paper ends by discussing innovative elements in the proposed approach, achievements, shortcomings and possible policy uses.     

Using Geographically Weighted Choice Models to Account for the Spatial Heterogeneity of Preferences

In this paper, we investigate the use of geographically weighted choice models for modelling spatially clustered preferences. We argue that this is a useful way of generating highly‐detailed spatial maps of willingness to pay for environmental conservation, given the costs of collecting data. The data used in this study come from a discrete choice experiment survey of public preferences for the implementation of a new national forest management and protection programme in Poland. We combine these with high‐resolution spatial data related to local forest characteristics. Using locally estimated discrete choice models we obtain location‐specific estimates of willingness to pay (WTP). Variation in these estimates is explained by characteristics of the forests close to where respondents live. These results are compared with those obtained from a more typical, two stage procedure which uses Bayesian posterior means of the mixed logit model random parameters to calculate location‐specific estimates of WTP. We find that there are indeed strong spatial patterns to the benefits of changes to the management to national forests. People living in areas with more species‐rich forests and those living nearer bigger areas of mixed forests have significantly different WTP values than those living in other locations. This kind of information potentially enables a better distributional analysis of the gains and losses from changes to natural resource management, and better targeting of investments in forest quality.     

简论熵和负熵与地球生态问题

本文简论熵和负熵与地球生态问题 ,指出生态系统和经济系统一样当属于热力学系统 ,它应遵从热力学定律 ,是一个适合于应用熵理论描述和研究的问题。