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.     

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.     

The Farm Diversification Discount

This article estimates the effect of diversification on farm values, where farms are valued relative to the median specialized farm having the same enterprise. Using data from the Agricultural Resource Management Study, the estimated diversification discount in agriculture is similar to the discount found for corporate firms. The results show that diversified crop/livestock farms had a diversification discount of 5.8% in comparison with specialized crop or livestock farms from 1999 to 2001. Commodity diversified farms had a diversification discount of 9.4% in comparison with commodity specialized farms.     

The Inefficiencies of Regionalised Milk Quota Trade

This paper estimates the inefficiencies associated with the regionalisation of the milk quota trade. An optimisation model is developed to estimate the economic value of quota. Quota values are aggregated to derive quota sale and purchase curves under two scenarios: first, where quotas can be traded nationally and second, where the trade of quota is regionally restricted. Quota trade is simulated and the consequent effects on supplier structure estimated. Through the derivation of sectoral cumulative cost curves it is possible to estimate the impact of regionalising quota trade on sector efficiency. The model is solved using National Farm Survey data from Ireland and the inefficiencies of regionalised quota trade in Ireland are estimated at €27 million. The paper concludes by discussing the implications of restricted quota trade, especially in the context of eventual quota removal.     

财政支出对我国农业增长的多途径影响

本文采用变系数生产模型,将全要素生产率中涉及各生产要素质量提升的部分剥离,从而识别财政支出通过不同途径影响农业增长的内在机制,并利用省级面板数据(1978-2015年31个省份)和县级面板数据(1993-2010年2495个县),从宏观和中观视角实证考察和比较了各改革阶段财政支出通过不同途径对农业产出的影响及其长期总体回报率,从而为政府合理分配农业财政支出提供参考。研究发现,每一单位当期农业财政支出的增加,能提高0.4个单位的当期农业产出,其中,通过全要素生产率途径的影响占到一半,通过提升化肥和农机质量的影响各约占四分之一,而通过改变劳动力和土地质量的影响很小。此外,财政支出的长期投资回报率达250%,加大农业财政支出,这将为农业持续增长提供新动能。     

Effect of Experimental Design on Choice-Based Conjoint Valuation Estimates

In this article, we investigate the effect of several commonly used experimental designs on willingness-to-pay in a Monte Carlo environment where true utility parameters are known. All experimental designs considered in this study generated unbiased valuation estimates. However, random designs or designs that explicitly incorporated attribute interactions generated more precise valuation estimates than main effects only designs. A key result of our analysis is that a large sample size can substitute for a poor experimental design. Overall, our results indicate that certain steps can be taken to achieve a manageably sized experimental design without sacrificing the credibility of welfare estimates.     

Implications of high food prices for poverty in Pakistan

The study estimates the impacts of rising world food prices on poverty in rural and urban areas of Pakistan. Household income and expenditure data for 2004/2005 is used to estimate compensated and uncompensated price and expenditure elasticities using the linear approximation of the almost ideal demand system. Taking the unexpected component of higher domestic food prices in 2007/2008, own and cross price compensated elasticities are used to derive the changes in the quantity consumed, food expenditure and impacts on poverty assuming the food crisis happened in 2004/2005. The results indicate that poverty increased by 34.8%, severely affecting the urban areas where poverty increased by 44.6% as compared to 32.5% in rural areas. The estimates show that 2.3 million people are unable to reach even one‐half of poverty line expenditures while another 13.7 million are just below and 23.9 million are just above the poverty line. In the short run, it is important to ensure food availability to these people. In the long run, the policy environment of subsidizing urban food consumers by keeping wheat prices lower than the international price, needs to be reconsidered to provide the right incentives to increase food availability.     

Food consumption dynamics: a nonparametric approach using maximum entropy estimation

We model dynamic consumer choice in a stochastic optimal control framework and show conditions under which observable market share data possess the Markov property. Using 30 years of annual aggregate milk consumption data differentiated by fat content, maximum entropy is used to estimate nonstationary transition probabilities showing how consumer tastes and preferences have changed over time. The maximum entropy approach allows for the estimation of a 4 × 4 transition probability matrix for each year of the sample. Results suggest that skim milk was an absorbing state over most of the sample but that the trend toward skim milk has decelerated and possibly reversed itself since 1998. Our approach provides a useful complement to existing parametric approaches to demand analysis when data are limited or the problem is ill‐posed.     

Welfare impacts of import controls on Botswana's horticulture

Botswana has, for the past two decades, used import controls (permits) to regulate horticultural imports, and thereby promote economic diversification through import substitution. This article estimates import demand equations to capture the impact of import controls on horticultural imports (oranges, potatoes, and onions) into Botswana, using data for 1974 to 2001. Parameter estimates are used to compute nominal protection rates (NPRs) and welfare effects. Model‐generated NPRs are estimated at 191%, 75%, and 109% for oranges, potatoes, and onions, respectively. Imports of oranges, potatoes, and onions declined by 32%, 29%, and 35%, respectively, due to the implementation of import controls. Over time consumer losses and quota rents rose while producer gains declined. Net social losses also increased, implying that import controls became increasingly burdensome. It is argued that import controls have not been very effective in promoting import substitution. The study is important for the trade liberalization debate in the Southern African Customs Union (SACU) and within the Southern African Development Community (SADC), where import permits and other nontariff barriers are pervasive, have proliferated, and are a major hindrance to intraregional trade.     

Comparing Open-Ended Choice Experiments and Experimental Auctions: An Application to Golden Rice

We use two experimental valuation methods to estimate consumer demand for genetically modified golden rice. The first is an open-ended choice experiment (OECE) where participants name the quantities of golden rice and conventional rice demanded at each of several price combinations, one of which will be randomly chosen as binding. This allows us to estimate market demand by aggregating demand across participants. This estimate of market demand also allows us to estimate own-price elasticity and consumer surplus for golden rice. Comparing willingness-to-pay (WTP) estimates from the OECE with those from a uniform-price auction, we find that OECE WTP estimates exhibit less affiliation across rounds, and the effects of positive and negative information under the OECE are more consistent with prior expectations and existing studies. We also find that, while auction WTP estimates more than double across five rounds, OECE WTP estimates are stable across rounds and are always roughly equal to those from the final auction round.     

Valuing Pre-Commercial Genetic Resources: A Maximum Entropy Approach

Genetic improvement has been a major contributor to agricultural productivity in the United States, but many questions about the economics of crop breeding, such as the value of pre-commercial germplasm, remain unanswered. This study estimates the marginal value of poorly characterized materials contained in the U.S. national germplasm system. Within the search theoretic framework, we apply a maximum entropy method to estimate the probability and the expected level of improvement in pest susceptibility relative to its best previously observed level. The results indicate that the lower-bound estimate of benefit is significantly higher than the upper-bound cost of conserving an accession.     

A Comparison of Conjoint Analysis Response Formats

A split-sample design is used to evaluate the convergent validity of three response formats used in conjoint analysis experiments. We investigate whether recoding rating data to rankings and choose-one formats, and recoding ranking data to choose one, result in structural models and welfare estimates that are statistically indistinguishable from estimates based on ranking or choose-one questions. Our results indicate that convergent validity of ratings, ranks, and choose one is not established. In addition, we find that people frequently use "ties" in responses to rating questions, and that the option not to choose any of the alternatives ("opt-out") affects some preference estimates.     

Joint Estimation of Risk Preferences and Technology: Flexible Utility or Futility?

A thought experiment is designed to investigate whether the structure of risk aversion (i.e., the changes in absolute or relative risk aversion associated with changes in wealth) can be estimated with reasonable precision from agricultural production data. Findings strongly suggest that typical production data are unlikely to allow identification of the structure of risk aversion. A flexible-utility parameterization is found to slightly worsen technology parameter estimates. Results also indicate that even under a restricted-utility specification, utility parameter estimates are biased. Further, their quality is much worse when shocks are not large or samples are small.     

Nutrition Transition and Changing Food Preferences in India

We present empirical evidence on how changes in food preferences have contributed to nutrition transition, where the dietary pattern of households shifts away from traditional staples. Using household-level time series cross-section survey data for India, we estimate time varying demand elasticities, revealing evidence of the declining importance of cereals in Indian household diets. The estimates show that Indian demand for cereals has become more income inelastic and price elastic. We also find that cereals are a substitute rather than a complement to animal products in household diets. Since changes in elasticities can only be attributed to variation in utility parameters, this indicates that cereals are losing favour with Indian households. These findings have implications for Indian food policy design and implementation.     

On the use of flexible mixing distributions in WTP space: an induced value choice experiment

In this study, we use data from an induced value choice experiment to compare estimates from mixed logit models in willingness to pay (WTP) space using different parameter distributional assumptions. Specifically, we test differences in WTP estimates when using flexible parameter mixing distributions (i.e. Legendre polynomials, step functions and splines) and conventional parameter distributions (normal and lognormal). Similar WTP estimates are obtained. However, we observe that WTP estimates are statistically different from the induced value when conventional distributions are assumed, but they are not when more flexible distributions are assumed. This suggests that flexible distributions can provide more reliable WTP estimates.     

黄河三角洲土地利用结构信息熵分异规律研究--以垦利县为例

以信息熵原理分析了垦利县土地利用的分异规律.结果显示:垦利县土地利用结构信息熵在1986-2003年期间有几次波动:1986-1990年基本保持不变,但保持较高水平(0.6961),1990年之后逐渐收敛,1993年达到最小值(0.6862),之后逐步升高,至2002年达到最大(0.6965),之后略有下降并趋稳定.信息熵在空间的分布以东部沿海的红光办事处和市畜禽场的信息熵最小,而垦利县城及以西地区,包括垦利镇、高盖乡和胜坨乡的信息熵较大.根据同期的社会经济数据,分析了影响信息熵变化因素,并建立信息熵变化模型.     

长株潭地区土地利用结构信息熵时空测度与演化

［目的］探讨区域土地利用结构的时空变化，为政府制定土地利用规划提供参考。［方法］基于信息熵的基本原理，利用2002—2014年长株潭地区各县（市、区）土地利用变更数据和相关社会经济资料，对研究区域土地利用结构的时间变化规律和空间分异特征进行了分析，并运用灰色模型进行了预测分析。［结果］（1）从整体上看，耕地、园地、林地、草地、水域及水利设施用地、其他土地所占比例呈递减趋势，城镇村及工矿用地、交通运输用地所占比例呈递增趋势。（2）土地利用结构信息熵在2002—2014年期间总体呈先下降后上升的变化趋势，从2002年的1350 3 Nat上升到了2014年的1362 3 Nat。（3）各县（市、区）土地利用结构的信息熵呈现出较大的时空差异。（4）运用灰色模型预测可知，到2026年土地利用结构信息熵出现上升趋势。［结论］当地政府必须高度重视，大力提高土地资源配置效率与集约利用水平，优化城市土地利用结构，合理布局城市用地，实现土地资源的可持续利用。     

SUPPLY RESPONSE IN THE AUSTRALIAN EXTENSIVE LIVESTOCK AND CROPPING INDUSTRIES: A STUDY OF INTENTIONS AND EXPECTATIONS*

Most of the supply elasticity estimates reported for Australian agriculture are derived from equations estimated using time series data and incorporating ad hoc assumptions about price expectations. The authors' aim is to compare previously obtained supply elasticity estimates with those derived using theoretically more acceptable survey data on both producers' intentions and price expectations. Surveys were conducted in three regions in N.S.W., namely, the Southern Tablelands, the South-West Slopes and a portion of the Western Division centred on Cobar. The results of the research show that there are no major differences between the supply elasticities derived using the traditional time series approach and those obtained using the survey data. This finding is reassuring, given the cost of collecting survey data.     

Least Squares and Entropy: A Penalty Function Perspective

Mathematical measures of entropy as defined by Shannon and cross entropy as defined by Kullback and Leibler are currently in vogue in the field of econometrics, primarily due to the comprehensive work of Golan, Judge, and Miller. An alternative interpretation of the entropy measure as a penalty function over deviations is presented, and a number of parallels are drawn with least squares estimators. It is demonstrated that both approaches may be applied to the general linear model. The causes of differences in estimated parameter values are described, and some suggestions for the formulation of entropy-based econometric problems are presented.