On the Opportunity Cost of Crop Diversification

Distance functions are increasingly being augmented, with environmental goods treated as conventional outputs. A common approach to evaluate the opportunity cost of providing an environmental good is the exploitation of the distance function's dual relationship to the value function. This implies that the opportunity cost is assumed to be non‐negative. This approach also requires a convex technology set. Focusing on crop diversification for a balanced sample of 44 cereal farms in the East of England for the years 2007–2013, this paper develops a novel opportunity cost measure that does not depend on these strong assumptions. We find that the opportunity cost of crop diversification is negative for most farms.     

Pricing-to-Market: Price Discrimination or Product Differentiation?

We employ a vertical differentiation model to examine the potential bias in pricing-to-market results when using export unit values aggregating differentiated products. Our results show that: (i) false evidence of pricing-to-market is always found when using unit values, whether the law of one price holds or not; and (ii) the size of the bias increases with the level of product differentiation. Our simulation results support those conceptual findings. Thus, some of the positive pricing-to-market results in the literature could be an artifact of the product heterogeneity embodied in unit values rather than evidence of imperfect competition.     

关于重庆市水价体制改革的思考

合理、有效的水价制度不但可以优化重庆市的水资源配置,而且还能减轻三峡库区的环境压力,乃至实现整个长江流域水资源的可持续利用。针对现行水价体制存在的问题,重庆市水价体制改革应该明确合理的改革目标,建立产权清晰的水权制度,并对水价结构和类型进行合理划分,最后再设计出区别对待不同用水类型的歧视性水价制度和不同用水量的阶梯式水价制度。     

Agricultural Commodity Price Shocks and Their Effect on Growth in Sub‐Saharan Africa

Commodity price shocks are an important type of external shock and are often cited as a problem for economic growth in Sub‐Saharan Africa. We choose nine Sub‐Saharan African countries that are heavily dependent on a single agricultural commodity for a significant portion of their income. This paper quantifies the impact of agricultural commodity price shocks using a structural non‐linear dynamic model. The novel aspect of this study is that we determine whether the response of per capita GDP for the selected Sub‐Saharan African countries is different to unexpected increases in agricultural commodity prices as opposed to decreases in prices. We conclude that there is very little evidence that an unanticipated price increase (decrease) will lead to a significantly different response in per capita incomes.     

Price Endogeneity and Food Demand in Urban China

Price endogeneity has been ignored in previous analyses of food demand in urban China. We exploit data provided by the China National Bureau of Statistics on agricultural commodity supply shifters and use reduced‐form price equations to account for price endogeneity. Applying our unique econometric approach to the analysis of provincial‐level food demand in China, we find strong statistical evidence of price endogeneity. Models that ignore price endogeneity result in substantially biased elasticities and misleading estimates of future food demand in China.     

A Meta‐Analysis on the Elasticity of Demand for Pesticides

There is an increasing policy interest in pesticide taxation schemes as a measure to reduce harmful effects of pesticide use. The effectiveness of such tax depends, however, on the price elasticity of demand for pesticides. Moreover, information on these demand elasticities and their determinants is of crucial relevance for policy‐making and normative modeling approaches. In this article, we present a meta‐analysis based on studies that have estimated pesticide demand elasticities in Europe and North America. Our meta‐analysis reveals that the own‐price elasticities of demand for pesticides are, with a median of ?0.28, significantly smaller than zero, but also significantly larger than ?1, i.e. to be inelastic. We find that the demand for pesticides for special crops is less elastic than that for arable and grassland. In addition, the demand for herbicides is more elastic than for other pesticides. Studies that consider only short‐term horizons and little flexibility for farmers to adjust to price changes generate significantly less elastic pesticide demands. The results also indicate that more recent studies identify lower pesticide price elasticities of demand. Furthermore, we find that peer‐reviewed studies tend to find more inelastic results compared to grey literature.     

黄河工程管理现代化建设探讨

在分析当前黄河工程管理在管理体制和运行机制等方面存在问题的同时,论述了“数字工程管理”的概念和建设的必要性及建设目标、建设内容等。总的建设思想是在继承传统工程管理绎验的基础上,敢于创新、与时俱进。在试点工程管理建设过程中,成熟一个项目推广一个。     

地勘单位产业发展的战略思考

文章结合湖南省地矿局的实际 ,分析了地勘单位产业发展的必要性 ,指出了目前地勘单位产业发展中存在着工勘业领域过广 ,优势产业不明显 ;多种经营业发展不稳定等问题。指出应努力使基地物业逐渐成为地勘单位经济亮点。认为确定优势产业是地勘单位产业发展的必然选择 ,而做强做大优势产业是地勘单位产业发展的关键。     

对勘察施工企业经营方式的辩证思考

作者认为经营方式落后于同行业的基准水平是许多勘察施工企业发展不景气的重要因素。文章通过分析勘察施工企业经营方式的基本现状 ,提出应辩证地看待勘察施工企业经营方式 ,在此基础上阐述了集约化经营的目标模式 ,并针对如何推进经营方式的转变提出四项基本措施。     

Price Dynamics in a Vertical Sector: The Case of Butter

We develop a reduced-form model of price transmission in a vertical sector, allowing for refined asymmetric, contemporaneous and lagged, own and cross-price effects under time-varying volatility. The model is used to investigate the wholesale-retail price dynamics in the U.S. butter market. The analysis documents the nature of nonlinear price dynamics in a vertical sector. It finds strong evidence of asymmetric retail price responses, both in the short term and the longer term, but only weak evidence of asymmetric wholesale price responses. Asymmetric retail responses play a major role in generating a skewed distribution of butter prices. The empirical results indicate the presence of imperfect competition at the retail level.