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].     

A Structural Econometric Model of Joint Consumption of Goods and Recreational Time: An Application to Pick-Your-Own Fruit

This article develops a structural econometric consumer demand model for goods, which have time and monetary costs, and where time spent obtaining the goods also enters into the utility function. The model is used to analyze customers' decision to buy pick-your-own versus preharvested strawberries at North Carolina pick-your-own fruit operations. The analysis distinguishes the effect of time as a resource constraint and time that provides utility. Demand for strawberries sold at the operations is price elastic, and demand for pick-your-own strawberries is less price elastic than demand for preharvested strawberries.     

A Simple Duality Model of Production Incorporatin Risk Aversion and Price Uncertainty

Proceeding within the framework of a linear mean-variance utility function, this paper outlines a duality model of production that incorporates risk aversion and price uncertainty. In contrast to risk models based on an expected utility function, this model provides a practical alternative to standard duality models for econometric research.     

Valuing a Change in a Fishing Site without Collecting Characteristics Data on All Fishing Sites: A Complete but Minimal Model

Resource economists are often asked to value a proposed change at one, and only one, recreational site; the model we develop and estimate is applicable for those cases. The application is valuing the elimination of fish consumption advisories on a large bay on Lake Michigan. The model is minimal but complete: complete in that the choice set is not restricted, minimal in that only two conditional indirect utility functions are estimated. It is utility-theoretic and one does not have to collect characteristic data on all of the other fishing sites in the region. Data include the number of trips each individual currently takes to Green Bay, answers to "would you prefer to fish Green Bay under conditions A or B?" and how often each angler says they would fish Green Bay under different sets of conditions.     

Budgeting and portfolio allocation for biosecurity measures

This paper presents a practical model for optimally allocating a budget across different biosecurity threats and measures (e.g. prevention or border quarantine, active surveillance for early detection, and containment and eradication measures) to ensure the highest rate of return. Our portfolio model differs from the common principle, which ranks alternative projects by their benefit cost ratios and picks the one that generates the highest average benefit cost ratio. The model we propose, instead, aims to allocate shares of the budget to the species where it is most cost‐effective, and consequently determine the optimal scale of the control program for each threat under varying budget constraints. The cost‐effectiveness of each block of budget spent on a threat is determined by minimising its expected total cost, including the damages it inflicts, and the control expenditures incurred in preventing or mitigating damages. As an illustration, the model is applied to the optimal allocation of a budget across four of Australia's most dangerous pests and diseases: red imported fire ants; foot‐and‐mouth disease; papaya fruit fly; and orange hawkweed. The model can readily be extended to consider more species and activities, and more complex settings including cases where detailed spatial and temporal information needs to be considered.     

Calibration of agricultural risk programming models using positive mathematical programming

Mathematical programming models of farmers’ cropping decisions must first be calibrated before they can be used to examine agricultural producer responses to policy changes. In this paper, we compare three calibration approaches for disentangling the risk parameter from the parameters of the cost function: one assumes a logarithmic utility function, while the others employ an exponential utility function. Historical crop insurance data for southern Alberta, Canada, are used to assess the calibration performance of the three approaches, and sensitivity analysis is implemented to test whether the changes in the optimal land allocation caused by the changes in the values of the parameters are practically reasonable. Only one of the three models is of practical use for policy analysis because it can recover the true values of the parameters and the results of sensitivity analysis are reasonable.     

“区块链”互助养老模式研究

中国是较早进入老龄化社会的发展中国家之一,为应对不可逆转的白发浪潮,互助养老作为养老模式的创新形式在政策推动和各地实践中迅速发展起来,但在实践中还有诸多问题亟待解决。在总结分析互助养老主要问题及原因的基础上,尝试结合新兴技术--区块链来改善互助养老的这些问题,打造"区块链"互助养老模式,形成线上线下联动,线上平台由实际运用层、智能运行层、数据储备层组成,以互助币为媒介通过线上平台了解、操作、交换互助服务,同时线下设备实时更新数据至区块链数据库,为老年人的健康保驾护航。     

Effect of yield and price risk on conversion from conventional to organic farming*

Although the benefits of organic farming are already well known, the conversion to organic farming does not proceed as the Dutch government expected. In order to investigate the conversion decisions of Dutch arable farms, a discrete stochastic dynamic utility‐efficient programming (DUEP) model is developed with special attention for yield and price risk of conventional, conversion and organic crops. The model maximizes the expected utility of the farmer depending on the farmer’s risk attitude. The DUEP model is an extension of a dynamic linear programming model that maximized the labour income of conversion from conventional to organic farming over a 10 year planning horizon. The DUEP model was used to model a typical farm for the central clay region in the Netherlands. The results show that for a risk‐neutral farmer it is optimal to convert to organic farming. However, for a more risk‐averse farmer it is only optimal to fully convert if policy incentives are applied such as taxes on pesticides or subsidies on conversion, or if the market for the organic products becomes more stable.     

Mass Education-led Growth and Non-agrarian Villages: Long-term Results of the Kerala Model

The advance of the human development perspective has seen education being established not just as a means of development but as an end in itself. This has created a case for focusing on mass education, even if it implies lower growth rates in the initial years. Such an approach is bound to influence the very pattern of development over the long run. For one, a sustained emphasis on mass education within a framework that assures adequate social security could increase the well-being of workers to a point where it affects the choices they make. In this paper a combination of a simple mathematical model and the experience of the south Indian state of Kerala is used to suggest some patterns of development over the long term that this approach throws up. It argues that the effects of this approach could be wide-ranging, including contributing to the creation of non-agrarian villages.     

基于"3S"的内外业一体化地籍变更模式研究

为促进现代测量技术和信息化成果在地籍管理工作中的应用,保证地籍数据的现势性,在传统地籍变更模式的基础上提出了基于"3S"的内外业一体化地籍变更模式.利用"3S"技术、无线电通讯技术、网络技术使得外业变更地籍调查与内业数据处理一体化,做到实地调查实地变更,遇到问题现场解决,与传统工作模式相比大大提高了地籍变更工作效率.     

土地利用规模和结构调整的环境影响评价模型研究

研究目的:构建一个可全面定量评价土地利用规模和结构调整相关环境影响的模型体系。研究方法:系统整合土地利用类型转移计算模型、多样性指数模型、土地生态服务价值计算模型、生态足迹和生态承载力评价模型等相关模型,并以上海市为例进行实证研究。研究结果:该模型体系比较全面地评价了上海市土地利用规划的环境影响,结果显示上海市的土地利用规划将导致区域土地利用结构明显变化,在一定程度上减少区域生态压力。研究结论:该模型体系能够客观评价土地利用规模和结构调整的相关环境影响,有一定的应用推广价值。     

Modeling the impact of technological change on nutrition and marketed surplus

This study develops and demonstrates procedures for modeling the impact of agricultural technology adoption decisions on consumption and nutrition in a subsistence‐farming context. The method is based on expected direct utility maximization (EDUM) formulation and incorporates subsistence quantities for broad aggregates of protein, calories, and other consumption goods. The method is applied to a hillside farming system of southern Honduras where new sorghum cultivars and erosion control techniques are being introduced. The expected direct utility maximization model allows the estimation of the effects of new technology on consumption and marketed surplus in situations where marginal values of products vary by state of nature and are affected by consumption and production choices. The introduction of the new technologies in southern Honduras results in improved nutrition and substantial increases in marketed surplus. These effects are due to simultaneous changes in output and consumption patterns. This work extends the subject of household modeling to problems with risk, and thus complements prior work in both the integrated analysis of production/consumption decisions and stochastic decision analysis.     

THE DEMAND FOR MEAT — AN EXAMPLE OF AN INCOMPLETE COMMODITY DEMAND SYSTEM*

Equations describing the demand for beef and veal, mutton, lamb, pork and chicken are estimated using the full information maximum likelihood estimator. Elasticity estimates are presented and the double logarithmic model is compared with a demand system which is derived from the indirect translog utility function. Estimates of the direct price and income elasticities are not particularly sensitive to model specification but the estimated cross-price elasticities are sensitive to the choice of functional form. The results indicate that the double logarithmic specification may be less satisfactory than the alternative presented in cases where restrictions on the parameters are imposed during estimation.     

Multi‐Criteria Analysis of Input Use in Agriculture

In this paper we present a methodology for the analysis of input use in the agricultural sector. The novelty of the theoretical model described here is that it has been developed considering a multi‐criteria environment. Thus, the optimal input use condition is determined by evaluating “multi‐attribute utility” and “multi‐attribute marginal utility”. We show how the approach adopted in this paper is a generalisation of the single‐attribute expected utility theory. The theoretical model developed is thereafter implemented in an empirical application that studies water for irrigation use as a particular case. The results show how multi‐attribute utility functions elicited for a sample of 52 irrigators explain differences in irrigation water use in relatively homogeneous agricultural systems, albeit exhibiting dissimilar partial utility functions for water use. We conclude that these differences come from the dissimilar weights that farmers attach to each attribute in the aggregate utility function.     

农户低碳化种植决策行为研究——基于河北省的调查数据

发展低碳农业是我国农业现代化的本质要求和必由之路,低碳种植是低碳农业的重要组成部分。我国低碳农业的发展并不尽如人意,其原因之一在于大多数农户在种植过程中仍然采用常规的农业种植方式。为研究农户低碳化种植的决策行为,该文以效用最大化理论为基础,建立了农户选择低碳化种植行为的效用函数模型,从理论上证明农户采取低碳化种植行为是一种有限理性行为,农户在选择种植方式时遵循了效用最大化原则,并结合前人研究推导了农业种植收入、农业种植行为以及种植预期对农户选择低碳化种植决策的影响趋势。根据对河北邯郸、保定和张家口3市360家农户的调查数据,运用Logit模型对调查数据进行计量分析。研究结果表明,对农户低碳化种植行为选择影响显著的因素有种植业收入比重、预期收益、现行种植行为、农户受教育水平、农业劳动力人数、政府政策以及同伴的种植行为。在此研究结论基础上,该文提出了促进低碳农业发展的相关建议。     

Russian Roulette at the Trade Table: A Specific Factors CGE Analysis of an Agri‐food Import Ban

In the summer of 2014 Russia imposed a ban on most agri‐food products from countries enforcing Ukraine‐related sanctions against Russia. We use a specific factors computable general equilibrium (CGE) model to simulate the short‐run impact of this retaliatory policy. The baseline is carefully designed to isolate the impacts of the ban on the European Union (EU), Russia itself and a selection of key trade partners. The modelling of the ban follows a novel approach, where it is treated as a loss of established trade preferences via reductions in consumer utility in the Armington import function. Not surprisingly, the results indicate that Russia bears the highest income loss (about €3.4 billion) while the EU recovers part of its lost trade through expansion of exports to other markets. An ex‐post comparison between simulation results and observed trade data reveals the model predictions to be broadly accurate, thereby validating the robustness of the modelling approach.     

A Simple Method of Incorporating Income Effects into Logit and Nested-Logit Models: Theory and Application

Substantive income effects are incorporated in a logit or nested-logit model by assuming that utility is a piece-wise linear spline function of residual income. Specific income data are not required, only income by category. Expected compensating variation is easily and accurately approximated by the difference between expected maximum utility in the proposed and initial state, multiplied by the inverse of the individual's initial marginal utility of money. This approximation is almost exact because although any policy can, in theory, cause an individual to jump income categories, for most policies this probability will be very small.     

森林公园游客环境行为管理模型之构建——以大熊山国家森林公园为例

游客环境行为对森林公园生态环境的影响日益凸显,一方面通过大熊山国家森林公园的实证分析,以问卷调查方式实地调研了该森林公园游客环境行为及其管理的现状,运用SPSS软件的相关性分析发现游客不良环境行为发生的频度和公园游客管理现状存在显著相关性;另一方面结合"刺激-反应"原理以及"破窗效应"的理论研究,尝试性的构建了森林公园游客环境行为管理模型,并以此为框架提出了大熊山国家森林公园游客环境行为管理的优化建议,如管理资源层面的突破,管理原则层面的提升等,以期为改进森林公园游客环境行为管理实践提供借鉴参考。     

A Sequential Choice Alternative to the Travel Cost Model

The travel cost model is the standard model used in the recreation demand area. This model assumes that the decision on the number of trips in a given time period (a season, for example) to a particular site is determined at the beginning of the time period. For certain types of recreation activity, it may be better to model the decision to take a trip to a given site as a function of the outcome of previous trips and the realization of random variables on previous trips (as well as travel and time costs). The spatial choice behavior itself may be sequential in nature rather than continuous. In this paper, a model is developed which specifies the choice of a discrete number of sequentially chosen trips to a given site as a function of site-specific variables and values realized on previous trips. This model improves upon the existing travel cost model by specifying discrete integer values for the number of trips, developing an explicit relationship between trips taken and the number of days spent on each trip, and allowing intra-seasonal effects to determine the probability of taking an additional trip. A comparison is made between the traditional travel cost model estimates of consumer's surplus and the estimates from this sequential discrete choice model.     

The Effects of Multiple Health and Nutrition Labels on Consumer Food Choices

Consumers face an increasing availability of information on health and nutritional aspects of foods, especially on food package labels. Previous research has identified that this information is positively valued, but the effect of presenting several items of information simultaneously is not well understood. We conduct a choice experiment to identify the effects of multiple health and nutrition information labels for two products representing a healthy and less healthy food choice. Although our consumers attach positive utility to most of the individual labels evaluated here, the simultaneous presence of more than one label only has positive impact on utility in one of nine possible cases. Therefore, promotion of multiple labels should not be considered beneficial a priori either from a regulatory or business perspective. In addition, results show that consumers show a higher willingness to pay for nutrition and health labels for less healthy products.