On the Comovement of Commodity Prices

We present strong evidence against the excess-comovement hypothesis—that the prices of commodities move together beyond what can be explained by fundamentals. Prior studies employ broad macroeconomic indicators to explain common price movements, and potentially correlated fundamentals are not controlled for. We use inventory and harvest data to fit a partial equilibrium model that more effectively captures the variation in individual prices. The model explains the majority of the comovements among commodities with high price correlation, and all of the comovements among those with marginal price correlation. Common movements in supply factors appear to play an important role in the observed comovements in commodity prices.     

AGRICULTURAL EXPORTS OF DEVELOPING COUNTRIES: ESTIMATES OF INCOME AND PRICE ELASTICITIES OF DEMAND AND SUPPLY

This paper provides new evidence on income and price elasticities of demand and supply of agricultural exports from developing countries, on the basis of (a) a consistent and fully specified supply and demand model, and (b) statistical estimation procedures not frequently used in the estimation of agricultural export functions. Estimates of price and income elasticities of demand for aggregate agricultural exports for all developing countries taken together — as distinct from individual exporting countries — are found to be low; moreover, export price as distinguished from non-price factors plays a relatively insignificant role in increasing export supply. Hence, an attempt by all developing countries to expand traditional agricultural exports with low price elasticity of demand may not yield rising earnings for all; but in fact may result in falling export revenues. Insofar as individual exports of all developing countries (not individual countries) are concerned, income and price elasticities of demand for such tropical commodities as tea, coffee, cocoa and bananas are also found to be low, except for new, non-traditional exports like pineapples. This indicates the importance of diversification of agricultural exports as a vehicle for their future growth.     

WELFARE IMPLICATIONS OF MORE ACCURATE RATIONAL FORECAST PRICES

Models are constructed to assess the welfare effects for producers, consumers and society of producers using forecast prices based on more accurate estimates of variables causing shifts in the demand for and supply of commodities. The basic model is a stochastic cobweb model in which producers' forecast price is the rational forecast price. The model is extended for many commodities, for partial producer response to more accurate forecast prices, and to include stock holding. In terms of economic surplus, producers and consumers gain from more accurate estimates of demand shift variables, producers gain and consumers lose from more accurate estimates of supply shift variables, and in both cases there is a net society gain.     

Demand System Estimation with Upward-Sloping Supply

There are three important implications of this work. First, demand systems estimates that overlook supply response are as subject to simultaneous equations bias as single ad hoc demand equations. Theil shows theoretically that assuming supply curves are perfectly elastic, when in fact they are not will underestimate price responsiveness in demand equations. An empirical example is presented that demonstrates that the price elasticities generally increase when upward-sloping supplies are assumed.
Second, the iterative testing procedure presented may provide direction for model building when the true structure of the system is unknown. For example, the results of the Wu-Hausman test indicate that assuming chicken supply is perfectly elastic in a model of the Japanese livestock industry is justified. The results also indicate that the supplies of Wagyu beef, dairy beef, pork and fish are upward-sloping and therefore should be modeled as endogenous variables in the demand system.
Third, the results emphasize the sensitivity of projections of Japanese beef imports to the assumptions underlying the demand system. If perfectly elastic meat supplies are assumed for an analysis of reducing Japanese beef import liberalization, the results will likely underestimate the impacts on beef imports.
In summary, the supply curves for agricultural products tend to slope upward within the time periods used for traditional policy analysis and demand system estimation, which in turn implies that prices are determined endogenously within the system. Endogenous price determination is contrary to the assumptions that underlie the theoretical foundations and many empirical applications of demand systems. We present a methodology to test for and adjust demand systems for endogeneity. The importance of this adjustment is demonstrated by using an analysis of the liberalization of the Japanese beef market.     

Notes on farm‐retail price transmission and marketing margin behavior

Perfect farm‐retail price transmission sometimes is taken to mean an elasticity of price transmission (EPT) equal to 1. We show that this definition is inconsistent with Gardner's (1975) model. We also show that the absolute marketing margin (defined as the difference between the retail price and farm price) responds differently to shifts in retail demand, input supply, and technical change in the marketers’ production function than does the relative marketing margin (defined as the ratio of the retail price to the farm price). The empirical implications of these results are discussed in some detail.     

茶籽油供需影响因素与弹性分析

依据经济学的需求和供给的基本原理,首先从价格、收入、替代品的价格及可获得性、消费者偏好和购买者数量等因素对茶籽油市场需求特性进行分析;其次从投入品价格、技术进步、相关物品的价格、政府政策和气候条件等5个方面对茶籽油供给特征进行深入剖析;然后,对茶籽油需求价格弹性、需求收入弹性和供给价格弹性进行分析;最后提出相应的政策建议。     

世界石油供应格局演变及价格走势分析

世界石油资源地域分布极不平衡,受资源丰度、勘探进展及开发强度等因素影响,世界石油供应格局发生了深刻变化。目前世界石油供应多元化的格局不仅形成,而且正不断得到强化。在供应多元化的基础上,石油市场构成已从垄断性向竞争性转变,供求关系将在决定油价方面发挥积极作用,但投机行为仍将左右国际市场油价变动的步伐和幅度,一定范围内的油价波动将在所难免。     

森林碳生产的激励机理分析

分析指出森林碳生产的激励原因在其经济属性,包括公共物品特性与生产的正外部性;运用供求曲线对森林碳生产进行经济解释;论证了产权制度安排与碳价格给付的森林碳生产激励办法;指出产权制度安排激励办法的现实困难,提出尽快开征碳税的建议。     

Price elasticity of water allocations demand in the Goulburn–Murray Irrigation District*

Bid prices for the demand and supply of water allocations between 2001 and 2007, and average monthly prices paid for water allocations from 1997 to 2007 in the Goulburn–Murray Irrigation District are analysed to estimate price elasticities. Based on bid prices, the price elasticity of demand for water allocations appears highly elastic, with elasticities strongly influenced by the season and drought. The price elasticity of supply for water allocations is also elastic, albeit less elastic than demand. Using actual prices paid, water demand is negatively related to price and is inelastic, and appears to be most influenced by demand the previous month, drought and seasonality factors.     

新一轮国际粮食价格上涨：原因及对中国市场的影响

[目的]随着中国粮食进口不断增加,国内外市场联系越来越紧密。2020年下半年以来,国际市场粮食价格快速上涨,对国内粮食市场产生一定影响,分析国际市场价格上涨的原因和影响对确保国内粮食供应稳定、保障国家粮食安全具有重要意义。[方法]文章分析了2019年以来小麦、大米、玉米、大豆4种粮食产品的国内外价格走势,从供需状况、贸易政策、气候变化等因素分析国际市场价格波动的原因,并探讨了国际价格对国内价格的影响。[结果]当前全球主要粮食品种供应充足,库存仍处于较高水平,此轮国际粮食价格上涨主要是受到美国等发达国家宽松的货币政策以及疫情后全球消费逐步回暖的影响;但国际市场价格上涨对中国市场的影响总体有限,国内小麦、大米、玉米价格上涨的主因是国内消费回暖和生猪产能恢复带动的饲用需求快速增长,油用大豆受国际市场的影响较大。[结论]为稳定国内粮食市场,避免国际市场的冲击,中国要进一步提升粮食综合生产能力,强化科技支撑,加强粮食储备管理,健全政策支持体系,并引导居民建立科学的消费观念。     

Econometric analysis of expected price formation

The current report analyses the process of producers' expected price formation through the estimation of supply functions, using vegetables and green tea in Japan as an example. At first, theoretical analysis shows that the factors which transform the producers' expected price formation from the lagged expectation to the rational expectation are as follows: decrease in information price, increase in managerial ability and/or organizational innovation, rightward shift of supply curve, and increase in price elasticity in supply curve. Second, supply functions are estimated by using the price expectation formation which include the rational expectation and the lagged expectation as its extreme form. Consequently, producers' price expectations were found to approach the rational expectations in the case of Chinese cabbage, lettuce and green tea, whose supply curves show high price elasticities, and whose producers' organizations gather price information and monitor the production more than other crops taken in this paper.     

岳城水库供水管理中存在的问题与对策

作为水利工程供水体系的重要环节,做好供水管理,对缓解水资源供需矛盾和保障供水安全起着至关重要的作用。基于对岳城水库供水现状的分析,对水利工程供水管理中存在的问题及成因进行了深入的探讨,提出了深刻理解做好供水管理工作对流域经济社会可持续发展的重要意义,以及规范用水秩序、提高岳城水库的供水保障能力,加快水价调整、促进节约用水和水资源合理配置,实行科学水价制度、保障工程效益的发挥的对策建议,以期实现流域水资源的可持续利用和经济社会的可持续发展。     

NEGATIVE SUPPLY RESPONSE AND THE ROLE OF PRICE EXPECTATIONS IN A TWO-PERIOD MODEL OF CATTLE PRODUCTION

This paper incorporates a representation of producers' price expectations (ARIMA) in a two-period production process to characterise short-run cattle supply. The model provides a framework for examining the role of biological factors and changing expectations of future cattle prices in generating a negative short-run supply response. The biological link between cattle generations requires the farmer to make a decision between production today and production tomorrow. This decision is based on a trade-off between the possibilities of increasing current profit levels by increasing current output weighted against the possibilities of increased future profit by maintaining animals in inventory under the expectation of future price increases. Application of the model to Canadian data for the period 1978-81 shows that the necessary condition for a negative supply response exists, but that the total supply elasticity remains positive.     

How to Understand High Food Prices

Agricultural price booms are better explained by common factors than by market‐specific factors such as supply shocks. A capital asset pricing model‐type model shows why one should expect this and Granger causality analysis establishes the role of demand growth, monetary expansion and exchange rate movements in explaining price movements over the period since 1971. The demand for grains and oilseeds as biofuel feedstocks has been cited as the main cause of the price rise, but there is little direct evidence for this contention. Instead, index‐based investment in agricultural futures markets is seen as the major channel through which macroeconomic and monetary factors generated the 2007–2008 food price rises.     

Futures markets and price stabilisation: An analysis of soybeans markets in North America

The objective of this paper was to determine whether the futures markets have a stabilising or destabilising impact on soybean's spot prices in North America. Directed acyclic graphs (DAGs) are used to test for causality between futures prices, spot prices and ending stocks, followed by time series econometric analysis. The DAGs point to the two-way causal link between futures and spot prices and a lack of a causal link between inventory/stocks and spot price volatility. Time series results, including cointegration, vector error correction, impulse response and variance decomposition analysis, indicate a large impact from futures markets on the level and volatility of soybean spot prices in both the short and long run. These results have potentially important implications, as the impact of commodity price volatility is typically asymmetric across different actors. Farmers, for example, unlike speculators, utilise price risk management (PRM) instruments such as futures markets to mitigate price risks and appear to suffer from intensified volatility precisely because of their use of these instruments. Therefore, additional policies to cope with commodity price volatility, such as direct price controls or mitigation of consequences, can have critical stabilising functions supporting farmers' welfare and regional (rural) development.     

Optimal Markup Decisions under Demand Uncertainty

This article examines the consistency with economic theory of a rule of thumb in which a risk-averse firm facing demand uncertaintly sets its price based on a percentage over the price paid to farmers. A testable set of comparative static results determines how the optimal markup is influenced by shifts in key parameters affecting the firm: expected demand, demand uncertainty and average variable costs. The model is tested using data from the wholesale markets for organic lettuce, broccoli and carrots. The results demonstrate that risk-averse wholesalers raise markups as expected demand increases and reduce them as uncertainty increases, consistent with risk-averse behavior. The empirical models show that produce marketing agents monitor shifts in expected demand and demand variability when adjusting markups. Expected demand has a greater impact on markups than demand variability.     

Economic impacts of El Niño southern oscillation: evidence from the Colombian coffee market

El Niño Southern Oscillation (ENSO) is a naturally occurring phenomenon that affects weather around the world. Past ENSO episodes have had severe impacts on the economy of Colombia. We study the influence of ENSO on Colombian coffee production, exports, and price. Our structural econometric specification is consistent with an economic model of the market for Colombian coffee which, in the short run, is characterized by a downward‐sloping demand curve and by a vertical supply curve. We show that El Niño (i.e., positive shocks to ENSO) is beneficial for Colombian production and exports and decreases the real price of Colombian coffee. On the contrary, La Niña (i.e., negative shocks to ENSO) depresses Colombian coffee production and exports and increases price. However, the overall impact of ENSO shocks is small. Both in the short run and in the long run, shocks to international demand for Colombian coffee are more relevant than supply‐side shocks in Colombia in explaining the dynamics of the price of Colombian coffee. Our results suggest that a given coffee price shock can have beneficial, detrimental, or negligible effects on the Colombian economy, depending on its underlying cause. As a consequence, policy responses to coffee price shocks should be designed by looking at the causes of the shocks.     

沈阳市城镇居民生活用水需求影响因素分析

利用时序数据及沈阳市康平县城镇居民生活用水的截面数据,对沈阳市城镇居民生活用水需求的影响因素进行实证分析,估计其需求价格弹性、需求收入弹性及需求教育弹性。估计结果明显有别于其他地区的研究结果,建议沈阳市应根据城镇居民生活用水水价偏低、收入弹性较大的实际,同时考虑到居民的承受力,调高水价时采用递增的阶梯式水价或补贴低收入用水户等政策,合理发挥价格杠杆的作用,同时还应注意到负的需求教育弹性,加强对居民的节水宣传教育。     

The nature of the research-induced supply shift

Differences among firms in a competitive industry can affect the shape of the industry supply curve. It is necessary to know how both production costs and rents are affected by research. Industry response to research will be different depending upon whether entry occurs. If the effect of entry is ignored, then the price decline from research will be overstated. Industry marginal returns can be positive with purely yield-increasing research, even when industry demand is inelastic. Standard formulas for calculating producer surplus based on linear industry supply and demand curves are strictly valid only if the analysis is restricted to short-run equilibrium behaviour.     

Asymmetric Margins in Prices and Retail Supply Chain Integration: The Spanish Vegetable Case

Several studies have observed asymmetric behavior between sale prices in the supermarket and the price paid to the farmer. This article presents the consequences derived from a simplified framework considering a scenario in which the retailer wishes to maintain balanced profits due to external pressures or because the retailers' strategy to differentiate themselves from the competition requires greater integration in the supply chain. It is shown that the price-fixing decision of the distributor may depend on the risk, measured by the relationship between demand elasticity and variable costs, as a result of uncertainty in consumer response to price variations. This risk arises from the existence of supply that is highly changeable in the short term and demand that is unpredictable.