A roller coaster ride: an empirical investigation of the main drivers of the international wheat price

Over the last decade, commodity prices have registered substantial booms and busts marked by extreme volatility. Wheat in particular, one of the main nonoil commodities, has registered a roller coaster in price levels which seems to be inconsistent with supply and demand fundamentals. To acutely investigate the drivers of wheat prices and quantify their impact, a vector error correction model (VECM) has been used. The exogenous variables have been distinguished into four groups: market‐specific factors, broad macroeconomic determinants, speculative components, and weather variables. The quadriangulation of the determinants will enable us to better understand the movements in wheat price and identify the specific role of each component. The results show that a mix of factors are contributing to wheat price movements, including speculation, global demand, and real effective exchange rate.     

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.     

Monetary policy shocks and the dynamics of agricultural commodity prices: evidence from structural and factor‐augmented VAR analyses

Fluctuation in commodity prices is a significant and timely issue to be studied. This study is to examine the impact of monetary policy and other macroeconomic shocks on the dynamics of agricultural commodity prices. The major contributions of this study are twofold. First, unlike other studies that use indexes, this study analyzes the commodities individually, affording the inclusion of commodity‐specific fundamentals such as the level of inventory—an important determinant of commodity price—in a structural VAR framework. Second, it exploits a rich data set of agricultural commodity prices which includes commodities that are usually overlooked in the literature, and extracts a common factor using the dynamic factor model to understand the extent of comovement of the prices and to gauge the extent to which macroeconomic shocks drive the “comovement” in a factor‐augmented VAR (FAVAR) framework. The findings show that monetary policy, global economic conditions, and the U.S. dollar exchange rates play an important role in the dynamics of agricultural commodity prices.     

Co‐movements in commodity prices: a note based on network analysis

This article analyses co‐movements in a wide group of commodity prices during the time period 1992–2010. Our methodological approach is based on the correlation matrix and the networks inside. Through this approach we are able to summarize global interaction and interdependence, capturing the existing heterogeneity in the degrees of synchronization between commodity prices. Our results produce two main findings: (a) we do not observe a persistent increase in the degree of co‐movement of the commodity prices in our time sample, however from mid‐2008 to the end of 2009 co‐movements almost doubled when compared with the average correlation; (b) we observe three groups of commodities which have exhibited similar price dynamics (metals, oil and grains, and oilseeds) and which have increased their degree of co‐movement during the sampled period.     

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.     

High food commodity prices: will they stay? who will pay?

Much of the public discussion of the food price crisis has focused on the sharply increased use of food commodities for biofuel production, framing debate in simple food versus fuel terms. Reality is more complex. Multiple forces drove food prices to high levels and, according to findings we report in this article, these forces will sustain high prices over the medium term. We also find that the distinction between high world prices for food commodities and the consumer costs of food is an important one to make. Food consumers do not buy raw food commodities at international prices. The degree to which the price of traded food commodities and the price of food are related depends on a long list of factors, most of which operate to dampen price transmission. In the search for appropriate policy response, it is essential to measure consumer effects correctly and to apportion properly the causes of current high prices.     

Do the EU countries import at the same price? The case of coffee

The establishment of the Economic and Monetary Union was expected to determine price convergence in the market of the European Union, leading to the equilibrium theorized by the law of one price. This article investigates prices convergence in the coffee market among European importers. Coffee is not only a tradable and traded good, but also one of the most valuable traded commodities. We account for different qualities of coffee in a hedonic regression model, which isolate and remove the effects of factors that might affect price dispersion. Adjusted import prices result to be significantly different between European Member States, and do not support the hypothesis of a deepening European market integration.     

THE RELATIONSHIP BETWEEN WORLD PRICE INSTABILITY AND THE PRICES FARMERS RECEIVE IN DEVELOPING COUNTRIES

World prices for agricultural commodities are traditionally unstable, but they were particularly turbulent during the late 1970s and early 1980s. This paper uses available post-War data on individual commodity prices to test whether world price instability is increasing, and to examine its impact on the prices producers receive in developing countries. It is found that the recent turbulence was more a statistical fluke than the beginning of any longer-term increase in market instability. Further, while the variability in world prices has been almost entirely transmitted to developing countries in the dollar value of their export unit values, it has not been fully transmitted to average producer prices. Real exchange rates, domestic marketing arrangements and government intervention have acted to buffer price movements for producers in many developing countries.     

Nudging farmers in crop choice using price information: Evidence from Ethiopian Commodity Exchange

The lack of reference price information is often regarded as one of the most pervasive aspects of incomplete commodity markets in developing countries. Previous studies on the effects of price information emphasize the market participation and performance of rural households. This paper argues that access to reference price information influences farmers’ crop choice decisions, the most important decision in farming activity. The study exploits the variation in timing and spatial distance of the publicly run Ethiopian Commodity Exchange (ECX) price tickers as an indicator for variation in the intensity of access to reference price information among rural villages in Ethiopia. The paper finds that access to price information increases the average farm-gate prices for traded commodities and incentivizes farmers to allocate more land, fertilizer and improved seeds to commodities traded in the ECX. It also nudges farmers to produce more of the traded commodities, increasing the output share of ECX-traded commodities.     

A Statistical Analysis of Wheat Price Fluctuations in England: 1685–1850

For some commodities and time periods, the analysis of price fluctuations must necessarily rely on the existence of price data alone. A theory applicable in such circumstances is outlined for commodities that are storable, traded in open markets and subject to net supply shocks which are heterogeneously distributed across the months of the year. Market prices are predicted to vary autoregressively except at times when wheat stocks become negligible and observed market prices exceed threshold prices (which may themselves differ across months). The model is applied to a monthly time series of wheat prices for southern England from 1685 to 1850. The autoregressive parameter and the threshold prices are estimated, substantial empirical support being found for the models tested. Historical events from the late seventeenth century through to the continental wars in the late eighteenth and early nineteenth centuries are used to illustrate the mechanisms underlying the theory.     

Price relationships between qualitatively differentiated agricultural products: organic and conventional wheat in Germany

Organic agriculture, which produces commodities that can be qualitatively differentiated from conventional food products, has grown into an important market in many countries. The dynamics of commodity prices in both sectors are partly interdependent, but are also shaped by independent determinants and have rarely been studied. We analyze organic food markets and their interdependencies with conventional markets in the context of wheat markets in Germany, which have been subject to a number of fundamental changes during the last two decades. Based on institutional market characteristics, we suggest a flexible Markov‐switching asymmetric time series model. We find a pronounced temporal sequence of market phases that differ in their asymmetric dynamics and the extent to which the organic price is influenced by the conventional price. Organic wheat prices tend to be increasingly connected to prices of conventional wheat.     

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.     

RELATIVE PRICE VARIABILITY AMONG AGRICULTURAL COMMODITIES AND MACROECONOMIC INSTABILITY IN THE UNITED KINGDOM

This paper develops measures of relative price variability among agricultural commodities in the UK farm sector for the period 1956-88. Econometric tests of the hypothesis that relative price variability is positively correlated with instability in the macroeconomy are carried out. The results indicate that UK agricultural commodity prices become more volatile relative to one another when the economy-wide inflation rate increases and when aggregate output becomes more variable. These findings suggest that UK producers and consumers of domestically grown farm products experience increased risk and uncertainty in their production and consumption decisions during periods of macroeconomic instability. The effects of UK entry into the European Community are also examined; no evidence is found to suggest that adoption of the Common Agricultural Policy reduced year-to-year relative price variability among agricultural commodities.     

Linkages between natural gas,fertiliser and cereal prices: A note

We use structural vector autoregressions to analyse the dynamic effects of shocks to natural gas and nitrogenous fertiliser prices on three major cereal crops: maize, rice and wheat. We find that the response of cereal prices to natural gas and fertiliser price shocks has been relatively small, instantaneous and transitory. These findings suggest that crop prices may change rapidly in response to energy and fertiliser prices, even when there are no shifts in the underlying fundamentals in crop markets. Furthermore, because the effects of the shocks dissipate rather quickly, short-term measures to address swings in food prices may suffice.     

全球农产品价格波动中金融化因素探析

近年来金融化因素在农产品市场中不断深化并形成新的特点，大量流向农产品市场的资金通过衍生市场进行非传统投机，尤其是将指数基金作为主要手段。供求状况难以反映农产品价格波动，而期货价格与指数基金的投机大大推动了农产品价格波动。我国应针对农产品金融化特性做出相应的政策调整。     

A hybrid commodity price‐forecasting model applied to the sugar–alcohol sector

Accurate price forecasting for agricultural commodities can have significant decision‐making implications for suppliers, especially those of biofuels, where the agriculture and energy sectors intersect. Environmental pressures and high oil prices affect demand for biofuels and have reignited the discussion about effects on food prices. Suppliers in the sugar–alcohol sector need to decide the ideal proportion of ethanol and sugar to optimise their financial strategy. Prices can be affected by exogenous factors, such as exchange rates and interest rates, as well as non‐observable variables like the convenience yield, which is related to supply shortages. The literature generally uses two approaches: artificial neural networks (ANNs), which are recognised as being in the forefront of exogenous‐variable analysis, and stochastic models such as the Kalman filter, which is able to account for non‐observable variables. This article proposes a hybrid model for forecasting the prices of agricultural commodities that is built upon both approaches and is applied to forecast the price of sugar. The Kalman filter considers the structure of the stochastic process that describes the evolution of prices. Neural networks allow variables that can impact asset prices in an indirect, nonlinear way, what cannot be incorporated easily into traditional econometric models.     

Crop price comovements during extreme market downturns

This study develops and estimates mixture models of crop price comovements using copula functions, which allow for departures from normality during extreme market circumstances. The models also account for unique time‐series patterns inherent in crop price data. The results point to two main conclusions. First, mixture models appear to provide an easy‐to‐estimate approach for capturing real‐life crop price movements. Second, mixture models find that, during extreme market downswings, correlations in price movements strengthen by several orders of magnitude. These results suggest that structured securities assembled from different crops tend to lose diversified protection during extreme market downswings, the exact times when such protection is needed most.     

Retail Price Fixity as a Facilitating Mechanism

Previous theoretical explanations for retail price fixity show that fixed retail prices can be consistent with either competitive or imperfectly competitive behavior. We develop a conceptual model of retail pricing wherein fixed price points are facilitating mechanisms for tacit collusion. A non-cooperative equilibrium in fixed retail prices is supported through credible threats to revert to Nash pricing if cheating is suspected. We test the implications of this model using a two-stage, ordered probit approach in weekly supermarket pricing data. The results show that price fixity does support collusive equilibria among retailers, but other factors may also explain retail price behavior.     

Using a functional approach to test trending volatility in the price of Mexican and international agricultural products

In this article, we extend the traditional GARCH(1,1) model by including a functional trend term in the conditional volatility of a time series. We derive the main properties of the model and apply it to all agricultural commodities in the Mexican CPI basket, as well as to the international prices of maize, wheat, swine, poultry, and beef products for three different time periods that implied changes in price regulations and behavior: before the North American Free Trade Agreement (NAFTA; 1987–1993), post‐NAFTA (1994–2005), and commodity supercycle (2006–2014). The proposed model seems to adequately fit the volatility process and, according to heteroscedasticity tests, also outperforms the ARCH(1) and GARCH(1,1) models, some of the most popular approaches used in the literature to analyze price volatility. Our results show that, consistent with anecdotal evidence, price volatility trends increased from the period 1987–1993 to 1994–2005. From 1994–2005 to 2006–2014, trends decreased but the persistence of volatility increased for most products, especially for international commodities. In addition, we identify some agricultural products such as avocado, beans, and chicken that, due to their increasing price volatility trends in the 2006–2014 period, may present a risk for food inflation in the short run.     

The effects of real exchange rate depreciation on stochastic producer prices in low-income agriculture

This paper considers the effects of real exchange rate depreciation on stochastic agricultural producer prices in low-income agriculture. Conventional wisdom, that real depreciation achieved through nominal currency devaluation stimulates tradables production, does not universally hold in the presence of stochastic prices. In fact, real depreciation is only stimulative in two cases–importables that remain importable and nontradables that become exportable. GARCH estimation of time-series price data on several commodities from Madagascar support the hypotheses generated by the analytical model.