中国粮食价格波动的成因及经济效应分析

选取1978—2011年的年度数据,运用协整对中国粮价波动的成因进行实证。结果表明：粮食生产量、农业生产资料价格指数、居民消费价格指数、粮食消费量、国际粮食价格、广义货币量和粮食库存量对粮食生产价格影响显著;粮食生产量、居民消费价格指数、粮食净进口量对粮食零售价格影响显著。而粮价波动的经济效应：2种粮食价格对粮食产量的影响不同;粮价上涨农民得到的很少;不能确定物价与2种粮食价格是否有关。最后提出了相关政策建议。     

How do institutional market players matter in farmland pricing?

In this paper we analyse how institutional sellers within the privatisation process shape price formation in agricultural land markets by taking the German reunification as an example. These institutions sell the formerly state owned land within first-price sealed bid auctions, publish calls and obtained prices, and are hypothesised to exploit their market power. Based on the conceptual framework of hedonic pricing models, we use a spatio-temporal modelling approach to empirically quantify these impacts. We thereby control for land productivity characteristics, potential buyers and whether farmers purchase the land. We find that privatisation agencies sell at significantly higher prices, while one agency sells at lower prices to farmers.     

What Explains Agricultural Price Movements?

After 2005, commodity prices experienced their longest and broadest boom since World War II. Agricultural prices have now come down considerably since their 2011 peak, but are still 40% higher in real terms than their 2000 lows. This paper briefly addresses the main arguments on the causes of the agricultural price cycle. It broadens the scope of analysis by focusing on six agricultural commodities, and identifies the relative weights of key quantifiable drivers of their prices. It concludes that increases in real income negatively affect real agricultural prices, consistent with the Prebisch–Singer hypothesis and its predecessor, Engel's Law. Energy prices matter most (not surprisingly, given the energy‐intensive nature of agriculture), followed by stock‐to‐use ratios and, to a lesser extent, ex‐change rate movements. The cost of capital affects prices only marginally, probably because it not only influences demand, but also evokes a supply response. The added value of these results lies in that, when examined in tandem and against market fundamentals, they challenge the conclusions from uni‐dimensional approaches that often put disproportionate weight on an individual factor.     

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.     

Are Shocks Transitory or Permanent? An Inquiry into Agricultural Commodity Prices

This paper contributes to the contentious topic of whether shocks to agricultural commodity prices are permanent or transitory. This is an important issue with regards to forecasting, economic modelling of agricultural prices and risk management. Past studies have not accounted for important characteristics of agricultural prices that matter when testing whether shocks to prices are permanent or transitory. These include the presence or absence of a deterministic trend, the possible break in the trend, non‐stationary volatility, and the problem of the initial deviation of commodity prices from their long‐run mean or trend. We conduct a comprehensive test that incorporates all these characteristics known to plague agricultural commodity prices. Though the conclusion is mixed, the balance is in favour of agricultural price shocks being permanent in nature. This result departs from the general view that in theory, agricultural prices should be stationary, suggesting that the controversy of whether shocks to agricultural prices are temporary or permanent is not yet over.     

Tracing the Effects of Agricultural Commodity Prices and Food Costs

We estimate a system of product and input-demand equations for food-processing industries to trace the links among farm commodity prices, food-processing costs, and food prices. Disembodied technical change, which likely reflects increasing consumer demand for convenience and product variety, has sharply reduced agricultural materials demand relative to most other food-processing inputs. This implies weakening impacts of farm price shocks on food prices. But improving quality and falling relative prices for agricultural inputs, in combination with increasing factor substitution, has counteracted these forces to encourage greater usage of agricultural inputs in food processing, and limit these trends.     

World food prices and poverty in Indonesia

Spikes in international food prices in 2007–2008 worsened poverty incidence in Indonesia, both rural and urban, but only by small amounts. The paper reaches this conclusion using a multisectoral and multihousehold general equilibrium model of the Indonesian economy. The negative effect on poor consumers, operating through their living costs, outweighed the positive effect on poor farmers, operating through their incomes. Indonesia's post‐2004 rice import restrictions shielded its internal rice market from the temporary world price increases, muting the increase in poverty. But it did this only by imposing large and permanent increases in both domestic rice prices and poverty incidence. Poverty incidence increased more among rural than urban people, even though higher agricultural prices mean higher incomes for many of the rural poor. Gains to poor farmers were outweighed by the losses incurred by the large number of rural poor who are net buyers of food, and the fact that food represents a large share of their total budgets, even larger on average than for the urban poor. The main beneficiaries of higher food prices are not the rural poor, but the owners of agricultural land and capital, many of whom are urban based.     

期货市场、货币供应量对农产品价格波动的影响——基于对小麦、玉米、大豆粮食品种的实证分析

近年来我国农产品价格波动频繁,特别是短期内小宗农产品价格波动剧烈,在一定程度上影响了农业生产秩序和物价稳定.基于2010年1月至2014年4月小麦、玉米和大豆价格的月度数据,采用VAR模型实证分析了农产品期货价格和货币供给的增长在影响农产品价格波动方面的差异性,并提出稳定农产品价格异常波动的相关策略及方法.     

The effects of China's growth on the food prices and the food exports of other developing countries

This article explores the impacts of China's growth in the international markets of agricultural products along two dimensions: food price inflation and export growth in other developing countries. China's food imports of vegetable oils have grown dramatically over the last decade, linking China's economic growth to the recent increases in global food prices. If China is a source of global food price inflation, exporting countries will benefit whether they sell directly to China or not. These direct and indirect linkages are explored using a short‐run, partial‐equilibrium model of international trade in agricultural products in which consumer prices and trade costs are derived from bilateral trade flows. China's effects on food prices and exports are estimated by reducing Chinese food expenditures in 2007 by half, roughly China's level of expenditures in 1995. Results indicate that food prices as measured by CES price indexes in developing Asia, Africa, and Latin America would have been reduced by 1.27%, 0.32%, and 0.22%, respectively. China has been an important source of growth for exporters selling directly to China. There is no evidence of export growth due to an overall increase in food prices caused by China's growth.     

Measuring the functional efficiency of agricultural futures markets

This article presents a method for measuring the functional efficiency of agricultural futures markets in terms of social welfare using a standard futures market structural model. Employing the concept of social surplus, it can be shown that, when futures prices are used to estimate future spot prices, the errors in prediction produce to some degree resource misallocation, which in turn results in welfare losses. Therefore, the social welfare associated with the presence of futures markets can be measured using a Social Loss index. The indicator was calculated for the period 1975–2015 and for several subperiods, which allow us to analyse functional efficiency before and after the 2007–2008 spikes in the prices of agricultural commodities. Futures contracts for 12 products are evaluated. The products are grouped in three different categories: ‘soft products’, ‘livestock’ and ‘grains and oilseeds’. The results indicate that livestock contracts tended to be more efficient than the rest of the contracts during the whole period, but in 2008–2015 their efficiency decreased vis‐á‐vis the rest of the products. Nevertheless, 2008–2015 proved to be the most efficient subperiod, confirming the remarkable development of agricultural futures markets over time.     

Forecasting pseudo‐periodic seasonal patterns in agricultural prices

A seasonal model is proposed to forecast agricultural prices with pseudo‐periodic seasonal patterns, in which the length of the seasonal period does not remain the same over time. The seasonal effect at a season is defined as a function of the proportion of the seasonal period length elapsed up to that season, and the seasonal pattern is modeled by means of evolving splines to capture any dynamic process of change. Such a model is a useful tool to forecast seasonal behaviors. To illustrate the relevance of this modeling framework, the methodology is applied to weekly prices of tomatoes exported to German markets.     

Wheat stocks and the cointegration of wheat prices

We examine the effect of wheat stocks on the relationship between port and inland wheat prices in western Canada after the dissolution of the Canadian Wheat Board in 2012. Standard statistical tests find no evidence that the port price is cointegrated with inland prices. We argue that large harvests in 2013–2014 and 2014–2015 are responsible for this lack of cointegration. A simple theoretical model demonstrates how wheat stocks drive a wedge between inland and port prices. After including wheat stocks in the cointegrating vector, we find the expected cointegrating relationships between the port and inland prices. Using an error correction model, we show that a 10% increase in the wheat stocks reduces producer prices in Alberta and Manitoba by 6% and 4%, respectively. We conclude by discussing policy options for reducing the size of wheat stocks on the prairies.     

Evolving splines and seasonal unit roots in weekly agricultural prices

The univariate statistical properties of agricultural price series need to be examined as a first step in the analysis of price transmission mechanisms. However, in the case of weekly price series, increasingly available, the testing procedures usually applied in this step are not suitable to deal with evolving seasonal effects. In this study, a method of testing for seasonal unit roots in weekly series of agricultural prices is described. When the deterministic seasonal component does not remain constant over time, the restricted evolving spline model (RESM) is shown to be a useful parametric formulation to capture the deterministic seasonal pattern. Therefore, the RESM model should be included as a deterministic component in auxiliary regression for unit root tests at seasonal frequencies. This proposal is applied to three weekly series of Canary Islands banana prices. From the standard seasonal unit root tests, the null hypothesis is failed to be rejected at the 5% or 10% significance level at some seasonal frequencies for each one of the series. Once critical values are obtained by simulation exercises when the RESM model is included, the hypotheses of unit root are rejected at each one of the seasonal frequencies for all of the three series.     

A simple model of endogenous agricultural commodity price fluctuations with storage

A debate has been raging for centuries regarding the effects of interannual storage on commodity prices. Most analysts consider storage to function as a price stabilizer, while others place it at the core of an explanation of intriguing features of commodity price series, such as skewed distributions. Most studies have been developed in the context of the theory of competitive storage where random shocks affect supply or demand. Recently, the endogenous chaotic behavior of markets has become another possible hypothesis regarding the origin of commodity price fluctuations. We develop a nonlinear cobweb model with intra‐ and interannual storage, risk averse agents, and adaptive expectations. Like the theory of competitive storage, this nonlinear cobweb model with storage can reproduce some of the stylized facts of agricultural commodity prices (autocorrelation of first rank, low kurtosis, and skewness). In addition, the effects of storage on price variation are mixed. In the presence of interannual storage, chaotic price series show less variation compared to a situation without interannual storage but we find that storage contributes to the endogenous volatility of prices by making chaotic dynamics more likely.     

Evaluating price transmission between global agricultural markets and consumer food price indices in the European Union

This paper uses error correction models to evaluate the extent to and speed at which world agricultural commodity price movements affect consumer food prices in the European Union member states. We consider three types of world commodity price indices, each containing different commodities and weighting criteria. Results reveal a long‐run relationship between world agricultural commodity and consumer food prices in over half of the member states. Consumer prices in different member states and categories of member states respond differently to specific world price indices, suggesting that there are disparities in the structure and the efficiency of their food markets. The eurozone founders generally have lower transmission elasticities. This should be taken into account when predicting the impacts of extreme world price volatility and consumer food price rises, prompting governments to pay attention to the most vulnerable households.     

Agriculture's terms of trade: issues and implications

The article addresses (1) the issue of what agricultural commodity prices should be compared to if we are concerned with the welfare of agriculturalists, (2) the general absence of product quality adjustment when analysis is undertaken comparing agricultural to manufactured goods prices, (3) the extent to which energy prices are or will be the driver of both manufactured and agricultural prices, and (4) the importance of considering agriculture's terms of trade (TOT) against the service sector, since the service sector is typically the largest in the economy. It reflects on the basic question of whether the widespread perception “that agriculture's TOT secularly decline” is correct.     

Effects of supermarket monopsony pricing on agriculture

Potential effects of alleged monopsony pricing of farm food products by supermarkets on farm product prices, quantities, incomes and land values are assessed relative to competitive behaviour. A long‐run comparative static equilibrium model is used. For export‐competing and import‐competing products, the farm food input supply curve facing the supermarkets is close to perfectly elastic and this limits monopsony behaviour. At the margin, the opportunity to reallocate agricultural land between traded and nontraded farm products means a highly elastic supply function for nontraded food inputs facing supermarkets and very limited monopsony effects.     

中国与“一带一路”国家农产品价格关联性研究——兼论中美贸易摩擦的影响

本文采用溢出网络方法及2010—2018年大豆、小麦、玉米月度价格数据,实证分析中国与"一带一路"沿线国家间农产品价格的多维关联特征,并着重探讨中美贸易战对该价格关联性的影响。结果显示:(1)总体而言,中国与沿线国家间的小麦、玉米价格存在较强关联性,大豆价格关联性较弱,且关联程度在全球供给冲击和A股股灾期间显著上升;(2)中国主要是沿线国家大豆和玉米价格净溢出的接受者,2016年6月由小麦价格净溢出的接受者转变为传递者;(3)中国与沿线国家间的农产品价格关联性存在地区差异,其中与黑海地区及巴基斯坦间的关联度较高;(4)中美贸易摩擦促使中国加大与"一带一路"国家的农业合作,从而增强了彼此间的农产品价格关联程度。     

Hedonic pricing and the spatial structure of housing data – an application to Berlin

Housing prices are largely determined by physical location. By applying the outsample prediction accuracy of rental prices as evaluation criteria, we examine whether the choice of the hedonic model additionally depends on the spatial structure of housing data, i.e. accounting for locational effects by either district fixed effects or spatial econometric modelling. Our results show that a generalised spatio-temporal model outperforms a district fixed effects model only if the spatial density – the weighted mean distance to nearest neighbours – is relatively small. Moreover, we use the required density thresholds to deduce a pseudo indifference curve, thereby showing that the ratio of the weighted spatial distance-to-the mean district diameter increases with the mean sample size per district. This emphasises the role of data structure and district choices for model selection. Differences in data can thereby serve as an explanation for contradictory findings in literature, whether spatial econometric methods or simple district fixed effects are used.     

Food price increases and net food importing countries: lessons from the recent past

Recent increases in food and other commodity prices have highlighted concerns that many poor countries are net food importers and higher food prices would worsen their trade balances. In this article, we analyze the changes in food trade balances associated with the 32% increase in food prices from 2000/2001 to 2004/2005. We find a small deterioration in food trade balances of low‐income countries and an improvement in middle‐income countries. The deterioration is most severe for countries in conflict and small island states, so attention should be placed first on these countries and on a few very‐low‐income countries that are also vulnerable. Because low‐income countries as a group had much lower agricultural GDP growth rates than middle‐income countries, the answers to food vulnerability in low‐income countries should probably be addressed within the context of incentives for agricultural production.