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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.  相似文献   

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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.  相似文献   

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Searching an Ex Situ Collection of Wheat Genetic Resources   总被引:1,自引:0,他引:1  
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.  相似文献   

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对生态系统服务价值问题的思考   总被引:8,自引:1,他引:8  
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。  相似文献   

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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.  相似文献   

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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.  相似文献   

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Property valuation is crucial to real estate developers, financial institutions and buyers as it could help determine the financial viability, establish a fair value of a real estate scheme, and eliminate the risk of borrowing respectively. Advanced mathematical algorithms such as artificial neural network (ANN) and support vector machine (SVM) may open up new ways to improve the valuation accuracy. This research aims to present an overview of the potential suitability of the SVM technique for property valuation. It is proceeded by identifying the key variables which could affect the property price. An entropy‐based rating and weighting method has been presented with the aim of providing objective and reasonable weighting. Then, based on the key variables, the predictive ability of SVM is compared with multiple regression analysis (MRA) and ANN outcomes. The results obtained from practical case studies in Hong Kong and mainland China indicate that, entropy and SVM serve better function for factor weighting and property valuation respectively. Hence, an entropy and SVM based decision support system is proposed, in which the key variable selection and the price valuation are integrated.  相似文献   

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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.  相似文献   

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Unreliable and inaccurate property valuation has been associated with techniques currently used in property valuation. A possible explanation for these findings may be due to the utilisation of traditional valuation methods. In the current study, an artificial neural network (ANN) is applied in property valuation using the Lagos metropolis property market as a representative case. Property sales transactions data (11 property attributes and property value) were collected from registered real estate firms operating in Lagos, Nigeria. The result shows that the ANN model possesses a good predictive ability, implying that it is suitable and reliable for property valuation. The relative importance analysis conducted on the property attributes revealed that the number of servants’ quarters is the most important attribute affecting property values. The findings suggest that the ANN model could be used as a tool by real estate stakeholders, especially valuers and researchers for property valuation.  相似文献   

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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.  相似文献   

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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.  相似文献   

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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.  相似文献   

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简论熵和负熵与地球生态问题   总被引:5,自引:0,他引:5  
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。  相似文献   

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Choice models are used by applied economists for many purposes, such as non-market valuation or estimating willingness to pay for novel food and product attributes. Mixed-logit models allow researchers to account for preference heterogeneity and complex decision-making processes when modelling choices. In mixed-logit models, parameters of monetary attributes such as prices typically are assumed to follow a negative lognormal random distribution to ensure that the marginal utility of a price increase is strictly negative. However, this practice can cause means and standard deviations of welfare estimates to ‘explode’ to unfeasibly large levels, as the model assumes there are some marginal utilities of cost approaching zero. This paper examines whether cost non-attendance, which occurs when respondents ignore costs in stated-preference studies, could be a cause of inflated welfare estimates when a lognormal cost parameter is used. A two-class equality-constrained latent-class model is proposed, in which the cost parameter is fixed at zero for a cost non-attender class and is specified as a random lognormal parameter for cost attenders. This proposed model produces mean welfare estimates that are 17 times lower than a mixed-logit model with a lognormal cost parameter, and 10% lower than a model with a non-random cost parameter. These results suggest that cost non-attendance can result in inflated welfare estimates when employing a lognormal cost parameter, and that accounting for cost non-attendance could be a simple, parsimonious solution to this problem.  相似文献   

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