Evaluating the effectiveness of inter-regional trade and storage in Malawi’s private sector maize markets

This paper evaluates the effectiveness of the private sector maize marketing system in Malawi using threshold autoregression models. Two dimensions of maize market performance are evaluated: (1) inter-regional trade and spatial price transmission; and (2) storage and seasonal price relationships. In both cases, threshold autoregression models which account for nonlinearities predicted by economic theory are applied. Results indicate that spatial price transmission and seasonal price patterns in private sector maize markets in Malawi are generally consistent with long-run competitive inter-regional trade and storage behavior, and that in most cases shocks to long-run equilibrium are arbitraged away quickly. This suggests the private sector in Malawi is generally doing a good job of transporting maize from surplus to deficit regions and smoothing maize consumption between harvests.     

The empirical relevance of the competitive storage model

The empirical relevance of models of competitive storage arbitrage in explaining commodity price behavior has been seriously challenged in a series of pathbreaking papers by [Deaton and Laroque, 1992], [Deaton and Laroque, 1995] and [Deaton and Laroque, 1996]. Here we address their major criticism, that the model is in general unable to explain the degree of serial correlation observed in the prices of twelve major commodities. First, we present a simple numerical version of their model which, contrary to Deaton and Laroque (1992), can generate the high levels of serial correlation observed in commodity prices, if it is parameterized to generate realistic levels of price variation. Then, after estimating the [Deaton and Laroque, 1995] and [Deaton and Laroque, 1996] model using their data set, model specification and econometric approach, we show that the use of a much finer grid to approximate the equilibrium price function yields quite different estimates for most commodities. Results are obtained for coffee, copper, jute, maize, palm oil, sugar and tin that support the specifications of the storage model with positive constant marginal storage cost and no deterioration as in Gustafson (1958a). Consumption demand has a low response to price and, except for sugar, stockouts are infrequent. The observed magnitudes of serial correlation of price match those implied by the estimated model.     

Photoshop的常用存储格式分析

使用图像处理软件会遇到多种文件存储格式的选择问题，文章通过对十四种常用存储格式的介绍，详细说明了各种存储格式的特性和应用注意事项。     

创新服务平台资源汇集机制设计

创新资源规模、特征、存储调用等资源汇集情况影响创新服务平台影响力及服务质量、方向与速度,因此,设计科学的资源汇集机制成为研究重点。基于平台不同阶段功能要求,明确重点资源吸纳对象,提出平台面向主动挖掘及宣传吸引两类资源吸纳方式。利用计算机五元组模型,确定资源信息类型与功能,据此从供求视角设计两阶段资源筛选机制。采集30多家创新服务平台资源存储关键词,运用词频统计软件,组织多次讨论,确定资源存储标签,提出利用PLSA模型与Jaccard系数相结合确定资源信息主题及主题与存储标签匹配归属方法。研究可为创新服务平台创新资源汇集提供理论与方法支撑,并为后续供求匹配研究奠定基础。     

浅析电子商务企业发展的制约因素

电子商务正在迅速发展,由此也产生了很多问题,如产品质量问题,仓储配送问题,支付问题等。本文通过对某电子商务企业客服部的数据进行统计分析,探讨目前电子商务企业发展过程中存在的主要问题及可能的原因。     

蓝莓加工与贮藏保鲜技术

蓝莓可保护视力,预防脑神经老化,软化血管,抗癌、强心、增强免疫力,深受群众喜欢。蓝莓果实加工产品市场需求量较大,而蓝莓加工、贮藏保鲜技术可满足全球各个市场需求。基于此,主要围绕此技术展开分析与论述。     

Why does on-farm storage fail to mitigate price volatility?

We analyze the role of farm stock management on price volatility under liquidity constraints and heterogeneous price expectations. In commodity markets, speculative behaviors by stockholders tend to reduce price volatility, but this is not the case in certain agricultural markets, where speculation by farmers regarding decisions to sell or store grain is subject to liquidity constraints and heterogeneous price expectations. Like stockholders, most farmers sell grain if they expect a price drop in the near future, but unlike stockholders, they are not necessarily able to purchase grain if they expect a price increase in the next period. Heterogeneous price expectations can also lead to suboptimal storage decisions, further increasing price volatility. For these reasons, the storage management behavior of farmers often fails to mitigate price drops in the way that speculation by stockholders does. We merge historical data on maize prices and household storage collected in Burkina Faso in order to build a dynamic panel over the 2005–2012 period. We show that carryover from one season to the next is associated with unexpected price drops during the preceding lean season and that carryover is associated with more frequent unexpected price drops following the subsequent post‐harvest season.     

Storage losses,liquidity constraints,and maize storage decisions in Benin

This article estimates how storage losses from mold, insects, and other pests, combined with liquidity constraints, influence a smallholder farm household's decision to store maize on farm after harvest. We analyze panel data from 309 smallholders in Benin covering the 2011 and 2013 harvest seasons. Results suggest that smallholders are driven to sell at harvest time for different reasons, depending on their motivation for storing. In households that report direct consumption as their primary goal for storing maize, liquidity constraints, not storage losses, reduce the amount they store. In contrast, households that store maize with the intention of selling it later in the year appear unaffected by liquidity constraints. Instead, these households store less when they expect to lose more during storage. These results suggest that policies to provide liquidity will be more helpful in motivating storage among consumption‐oriented households. Households motivated to store for later sale will benefit from modern storage technologies that mitigate the operational costs associated with storage losses.     

The effects of direct storage subsidies under limited rationality: a general equilibrium analysis

We study here the effects of a public subsidy to private storage set up at world level. To simulate the welfare effects and impacts on market fluctuations of this subsidy, we use a dynamic Computable General Equilibrium model assuming imperfect expectations. We also perform different statistical analysis based on our CGE results and show that the storage subsidy can have the undesired effect of destabilizing agricultural markets, depending on the form of economic agents’ price expectations and on the structure of the shocks impacting the agricultural production.     

On the behavior of commodity prices when speculative storage is bounded

This paper investigates the implications of bounded speculative storage, storage bounded from below at zero and above at a capacity, on commodity prices. Binding capacity mirrors the non-negativity constraint on storage and leads to negative price spiking and higher volatility when the market is in deep contango, i.e. low current prices at high stock levels. With bounded storage there is no need to restrict storage to be costly to ensure a rational expectations equilibrium. This allows the model to cover a wide range of storage technologies, including free and productive storage. We also provide an alternative expression for speculative prices that highlights the key role of the storage boundaries. The competitive equilibrium price is the sum of discounted future probability weighted boundary prices. The boundary prices can be viewed as dividends on commodities in storage reflecting the realization of economic profits from storage.