Bayesian Estimation and Selection of Nonlinear Vector Error Correction Models: The Case of the Sugar-Ethanol-Oil Nexus in Brazil

Nonlinear adjustment toward long-run price equilibrium relationships in the sugar-ethanol-oil nexus in Brazil is examined. We develop generalized bivariate error correction models that allow for cointegration between sugar, ethanol, and oil prices, where dynamic adjustments are potentially nonlinear functions of the disequilibrium errors. A range of models are estimated using Bayesian Monte Carlo Markov Chain algorithms and compared using Bayesian model selection methods. The results suggest that the long-run drivers of Brazilian sugar prices are oil prices and that there are nonlinearities in the adjustment processes of sugar and ethanol prices to oil price but linear adjustment between ethanol and sugar prices.     

Including Imperfect Competition in Spatial Equilibrium Models

Following Martin's paper on quadratic spatial equilibrium models this paper presents ways to incorporate imperfect competition in these models by altering the objective function of the quadratic program. This paper shows how the standard Cournot and Slackelberg equilibria may be modelled. The paper also describes the new theoretical models of consistent conjectural variations and how they may be translated into quadratic spatial equilibrium models. Situations that are likely to be modelled are discussed and appropriate models are presented. More complicated equilibria that cannot be modelled by simple adjustment of the quadratic objective function are also discussed.
Aprés la composition de Martin sur les modeles de L'équilibre quadratique et spatial, nous presentons des moyens d'incorprer la compétition imparfaite dans ces modeles en modifiant la fonction objective du programe quadratique. Nous montrons comment on peut modeler les équilibres Cournot et Stackelberg. Nous décrivons aussi les nouveaux modeles théoriques des variations consistentes et conjecturales, et comment ils peuvent éytre traduits en modeles de l'équilibre quadratique et spatial. Nous discutons les situations qui peuvent probablement étre modelées et nous presentons des modeles qui nous semblent appropriés. Nous discutons aussi des équilibres plus compliqués qui ne peuvent pas étre modelés par un simple ajustement de la fonction objective et quadratique.     

Modeling winegrape prices in disequilibrium

This article presents an econometric model of winegrape prices which recognizes the existence of demand and supply imbalances in the Australian market. A “markets in disequilibrium” framework is employed to motivate modeling price changes as responding to variations in excess demand/supply. The disequilibrium price equation provides estimates of regional and varietal price discounts/premiums and a measure of the speed of disequilibrium price adjustment. The equilibrium assumption is rejected for the market and substantial differences between equilibrium and disequilibrium estimates point to the inaccuracies of assuming market clearing. Disequilibrium estimates point to significant differences between warm and cool regions and changing speed of disequilibrium adjustment over time.     

PRICE-LINKED FARM AND SPATIAL EQUILIBRIUM MODELS

The integration of detailed farm supply models with the basic spatial equilibrium model, is outlined. The direct linking of farm linear programming models with the spatial equilibrium model is achieved so that both prices and quantities are endogenous. Both the farm model and the spatial equilibrium model must be specified in primal-dual form to make the linkages. Limited details of the use of such a model in a study of a segment of the grain handling system in New South Wales are presented along with conclusions relating to the pricing of grain handling services.     

Threshold Cointegration in the Greek Milk Market

This article investigates the nonlinear adjustment between consumer and producer prices in the Greek milk sector using a threshold error correction autoregressive model. The results reject the null hypothesis of linear cointegration in favor of a 2-regime threshold cointegration model. A cointegrating relationship is expected only when equilibrium consumer price is decreased more than 24.12% or the equilibrium relative markup is squeezed more than 62.74%. In this case consumer prices have to increase faster than producer prices to restore the long-run equilibrium between consumer-producer milk prices.     

江苏泗阳县速生丰产林市场结构均衡分析

通过调查和分析处理泗阳县意杨速生丰产林分布状况与产业化过程中的林产工业结构状况 ,研究营林与林产工业之间的供给与需求关系 ,并运用产业组织理论和方法 ,力求达到速生丰产林在产业化进程中市场结构的均衡 ,从而提出相应的调整措施 ,以推动泗阳林业产业化进程的发展。     

INDUSTRIAL ORGANISATION FOUNDATIONS OF TRADE POLICY MODELLING*

General equilibrium models of Canada/US free trade have produced a wide range of predictions of the impact on the Canadian economy. This paper analyses the models from an 'industrial organisation' perspective, focusing on differences in assumptions about market elasticities and pricing behaviour. The approach succeeds in encompassing the range of predictions from the models. The results have implications for agricultural policy modelling.     

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。     

Evaluating the Market and Welfare Impacts of Agricultural Policies in Developed Countries: Comparison of Partial and General Equilibrium Measures

We revisit the question of choosing partial equilibrium or general equilibrium modeling in applied policy analysis in the context of evaluating the effects of a complete phase-out of the Common Agricultural Policy (CAP) of the European Union. We compare the results of three models—two three-sector general equilibrium models (one with an additional major distortion in the nonagricultural sector) and a two-sector partial equilibrium model. We find that the market effects of a complete phase-out of the CAP are quite comparable across these models. On the other hand, the measured welfare impacts may depend on the modeling choice.     

Dynamic factor demand equations in U.S. and Canadian agriculture

This research provides one of the first empirical estimates of a data-based dynamic factor demand model for American and Canadian agriculture. Models such as these deserve more widespread use in the empirical analysis of agriculture. These models have the advantage that they do not impose inappropriate dynamics on the data. Rather they permit the data to select the appropriate dynamics. We use a model originally developed by Anderson and Blundell. This model is a general first-order dynamic model which contains as testable hypothesis several simpler models. This model permits us to estimate the long-run agricultural production structure as a subset of the dynamic parameter estimates. We will test this long-run structure for symmetry, homotheticity and neutral technical change. The estimated models may be used to test for three alternative dynamic structures. In the limit, dynamics may not be needed and we can test for the static long-run equilibrium model. Two intermediate cases are the autoregressive and the partial adjustment models which are simpler than the general model but still include dynamics. Our results suggest that the long-run equilibrium model is unsatisfactory in both countries. A dynamic model is needed. In both countries, the two more restricted dynamic models are rejected. The general dynamic model is required. In Canada, the long-run equilibrium structure is homothetic with neutral technical change. In the United States, homotheticity is also accepted but neutral technical change is rejected.     

Modelling the EU sugar supply to assess sectoral policy reforms

We investigate the possible linkages between the EU sugar productionunder quota and the supply of C sugar. We calibrate the implicitcross-subsidy between in-quota sugar and out-of-quota sugar.The resulting supply specification is included in a computablegeneral equilibrium model of the EU economy detailing the agriculturalsector. We simulate the effects of the 2006 reform of the EUsugar regime and the effects of a ban on sugar export subsidies.Results suggest that the reform makes it possible to fill therequirements of the 2005 World Trade Organisation panel butthat further adjustment will be needed to eliminate all exportsubsidies as is scheduled for 2013.     

Comparing supply‐side specifications in models of global agriculture and the food system

This article compares the theoretical and functional specification of production in partial equilibrium (PE) and computable general equilibrium (CGE) models of the global agricultural and food system included in the AgMIP model comparison study. The two model families differ in their scope—partial versus economy‐wide—and in how they represent technology and the behavior of supply and demand in markets. The CGE models are “deep” structural models in that they explicitly solve the maximization problem of consumers and producers, assuming utility maximization and profit maximization with production/cost functions that include all factor inputs. The PE models divide into two groups on the supply side: (1) “shallow” structural models, which essentially specify area/yield supply functions with no explicit maximization behavior, and (2) “deep” structural models that provide a detailed activity‐analysis specification of technology and explicit optimizing behavior by producers. While the models vary in their specifications of technology, both within and between the PE and CGE families, we consider two stylized theoretical models to compare the behavior of crop yields and supply functions in CGE models with their behavior in shallow structural PE models. We find that the theoretical responsiveness of supply to changes in prices can be similar, depending on parameter choices that define the behavior of implicit supply functions over the domain of applicability defined by the common scenarios used in the AgMIP comparisons. In practice, however, the applied models are more complex and differ in their empirical sensitivity to variations in specification—comparability of results given parameter choices is an empirical question. To illustrate the issues, sensitivity analysis is done with one global CGE model, MAGNET, to indicate how the results vary with different specification of technical change, and how they compare with the results from PE models.     

Product Differentiation and Cost Pass‐Through

The present paper extends the existing literature on vertical price transmission and cost pass‐through by investigating the impact of product differentiation. We apply distance‐measures of product differentiation to a specific product market (yoghurt) within one country (Germany). Results from a panel‐error‐correction model for 30 products sold in 432 stores over a period of 312 weeks suggest that product differentiation explains a significant share of differences in cost pass‐through rates: more differentiated products command higher prices and are characterised by lower equilibrium cost pass‐through rates as well as more sluggish price adjustment.     

The role of retail market power and state regulations in the heterogeneity of farm‐retail price transmission of private label and branded products

Given the leading role of private label brands in the fluid milk market, it is of special interest to focus on possible differences in farm‐retail price transmission between private label and branded milk as well as the causes of heterogeneity. This article examines the heterogeneous effects of private label and branded products on price transmission in the fluid milk market using a panel threshold asymmetric error correction model. Results indicate that upward retail‐price adjustment is faster than the downward price adjustment for both private label and branded milk. The speed of adjustment of private label products is significantly faster than branded products in three different price regimes. We further investigate the reasons of heterogeneity in farm‐retail price transmission of private label milk. We find that both retailer market power and state pricing regulations contribute to the heterogeneity in asymmetric price transmission. Higher retailer market power causes retail prices of private label milk to rise faster and to fall slower. The existence of a state pricing regulation slows down the adjustment speed of retail prices of private labels back to the long‐run equilibrium, regardless of whether the retail price is low or high.     

SOLUTION OF SPATIAL TRADING SYSTEMS WITH CONCAVE CUBIC PROGRAMMING*

Standard spatial equilibrium activity analysis models, as developed by Takayama and Judge (1971), are based on linear supply and demand functions and fixed input-output coefficients. Such models are suitable for multiple market level trading systems where the fixed input-output coefficients are appropriate. A primal-dual price form of these models is developed in which the assumption of constant per unit costs of transformation is relaxed. In the case when the average cost curves of transformation are quadratic in nature the problem becomes one that will be termed cubic programming (that is, a cubic objective function and linear and/or quadratic constraints) which is solved in a concave region of the solution space. In the paper, the formulation of a simplified spatial equilibrium model with quadratic average costs of transformation is presented and solved. A discussion of possible applications of such a model is also presented.     

Agriculture’s Inter‐industry Linkages,Aggregation Bias and Rural Policy Reforms

As agricultural policy reform and its effects have become increasingly territorialised, analyses that attempt to explain or predict impacts need to be both more localised and to identify spill‐over effects. Local and regional general equilibrium approaches have become increasingly popular because they can extend predictions of policy shocks obtainable from partial equilibrium sectoral models to identify the wider effects. However, agriculture is usually described as a single sector in input–output accounts, whereas policy shocks that affect constituent commodities with differential impacts will have inter‐industry effects that are different to those implied by average input–output coefficients. Regionalisation of aggregated input–output tables adds further to these difficulties. The objective of this study is to develop a practical method for dealing with these problems. It describes the theoretical basis of aggregation bias and shows how it can be measured, in two contrasting case study regions in the UK and Sweden. Having established that this is a significant issue, a simple but effective procedure is demonstrated, based on additional information on variable costs, which transforms policy shocks from a direct change in agricultural output to that transmitted to the suppliers of inputs. This method provides an impact close to that which could be calculated if the general equilibrium system had indeed been disaggregated, and supports use of this approach in impact studies where insufficient time or funding are available for complete disaggregation of an agricultural sector’s regional accounts.     

Agent‐based Modelling of Climate Adaptation and Mitigation Options in Agriculture

Computer simulation models can provide valuable insights for climate‐related analysis and help streamline policy interventions for improved adaptation and mitigation in agriculture. Computable general equilibrium (CGE) and partial equilibrium (PE) models are currently being expanded to include land‐use change and energy markets so that the effects of various policy measures on agricultural production can be assessed. Agent‐based modelling (ABM) or multi‐agent systems (MAS) have been suggested as a complementary tool for assessing farmer responses to climate change in agriculture and how these are affected by policies. MAS applied to agricultural systems draw on techniques used for Recursive Farm Programming, but include models of all individual farms, their spatial interactions and the natural environment. In this article, we discuss the specific insights MAS provide for developing robust policies and land‐use strategies in response to climate change. We show that MAS are well‐suited for uncertainty analysis and can thereby complement existing simulation approaches to advance the understanding and implementation of effective climate‐related policies in agriculture.     

MORE ON WELFARE GAINS TO DEVELOPING COUNTRIES FROM LIBERALIZING WORLD FOOD TRADE

The common presumption that food-importing developing countries would be harmed by a liberalization of world food trade is questioned in this paper. Both theory and new empirical modelling evidence suggest the possibility of the opposite conclusion. Even if just advanced industrial countries were to liberalize their food trade, the present empirical analysis (using a model of world food markets) suggests that economic welfare and net foreign exchange earnings from food trade could improve for the vast majority of developing countries. The extent to which that gain would be greater if developing countries also were to liberalize their policies affecting food markets is shown as well. The analysis helps to reconcile differences between previous results using partial-equilibrium models and those derived from computable general equilibrium models.     

Investment Under Uncertainty and Dynamic Adjustment in the Finnish Pork Industry

A stochastic dual model of investment under uncertainty is used to investigate structural adjustment in the Finnish hog industry. Value function restrictions are found to be comparable to those in existing dual models assuming deterministic state variables. The model also allows for an asymmetry in investment response during capital expansion and contraction phases. Empirical results show that investments respond negatively to increased uncertainty and that labor adjusts more slowly during contraction phases than during expansions. Results on economies of size, uncertainty effects, and adjustment rigidities have important implications for hog industry response to Finland's entry into the EU.     

Markets and pro-poor agricultural growth: insights from livelihood and informal rural economy models in Malawi

This article presents the development of a set of programming models describing the major features of different rural livelihoods and of the informal rural economy they together make up in Malawi. The models allow for differentiated responses by different household types to change and for the partial equilibrium effects of consequent supply, demand, and price adjustments in labor and grain markets. The models provide insights into the relations between own‐farm and nonown‐farm activities in different households' livelihoods and in the informal rural economy as a whole, and are used to investigate possible impacts of increasing cash crop prices and of a more open rural economy. Impacts of these changes on the poor are found to be critically dependent upon supply and demand elasticities in labor and grain markets, but the poor could potentially suffer significant losses from increased openness of the local economy leading to increased expenditure by less poor households on imported goods and services.