Modeling price transmission between farm and retail prices: a soft switches approach

Vector error correction models (VECM) are used to model price transmission when farm and retail prices are cointegrated. To allow for nonlinearity in the cointegration process, researchers may specify thresholds to break the error correction process into regimes according to whether the retail price is above, below, or close to its equilibrium value given farm prices.  However, because the coefficients in a VECM can change when there is movement from one regime to another, the model can be discontinuous.  This implies sudden, “hard” regime changes. In this study, we extend the threshold VECM to include features of smooth transition autoregression (STAR) models. Our approach allows for gradual, soft regime changes.  An empirical application to retail cheese and farm milk prices is presented.     

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.     

Price shock transmission: evidence from the wheat‐bread market value chain in Ethiopia

This study assesses the degree of vertical price transmission along the wheat‐bread value chain in Ethiopia. This is pursued by applying a vector error correction model and an impulse response analysis using monthly price data for the period 2000–2015. Our analysis considers transmission of price shocks across different market levels, including from the international and domestic wheat grain markets at the upstream to the domestic wheat bread market at the downstream of the value chain. The empirical findings indicate that significant cointegration exists across prices of the different market stages. There is a transmission from international prices to domestic prices at downstream markets, in particular to flour and bread prices. Prices at upstream markets are largely influenced by the domestic wholesale market. In general, the speed of adjustment is quite slow with a half‐life of about one year for restoring the equilibrium price relationship. As price margins between the different market stages in the value chain have substantially decreased in the last 15 years, higher transmission, and thus exposure to international market shocks, can be expected in the future. The results also show that causal relationships exist between prices at different market stages—with the wholesale market identified as the key market level where prices and price expectations are formed.     

Higher fuel and food prices: impacts and responses for Mozambique

Rising world prices for fuel and food represent a negative terms‐of‐trade shock for Mozambique. The impacts of these price rises are analyzed using various approaches. Detailed price data show that the world price increases are being transmitted to domestic prices. Short‐run net benefit ratio analysis indicates that urban households and households in the southern region are more vulnerable to food price increases. Rural households, particularly in the North and Center, often benefit from being in a net seller position. Longer‐term analysis using a computable general equilibrium (CGE) model of Mozambique indicates that the fuel price shock dominates rising food prices from both macroeconomic and poverty perspectives. Again, negative impacts are larger in urban areas. The importance of agricultural production response in general and export response in particular is highlighted. Policy analysis reveals difficult trade‐offs between short‐run mitigation and long‐run growth. Improved agricultural productivity has powerful positive impacts, but remains difficult to achieve and may not address the immediate impacts of higher prices.     

Price transmission,asymmetric adjustment and threshold effects in the cotton supply chain: a case study for Vidarbha,India

This study examines price transmission asymmetries in Vidarbha's (India) cotton supply chain from 2002 to 2012. The analysis takes account of thresholds in price adjustments toward their long‐run equilibrium. The first stage considers the price dynamics between international and Indian domestic cotton prices. The second stage considers price transmission from domestic to farm gate cotton prices in Vidarbha. Results from the first stage indicate that Indian and international cotton markets are well‐integrated. In contrast, the second stage reveals significant threshold‐type nonlinearities as well as asymmetries in price transmission between domestic and farm gate prices. The short‐run dynamics suggest that the pass‐through from domestic to farm gate prices is larger when domestic prices decrease than when they increase. Moreover, back of the envelope calculations suggest that the loss in revenue for a typical farmer from a decrease in domestic price is larger than the gains from an increase in domestic price of the same magnitude. The implication is that traders benefit from price fluctuations at the expense of farmers. Evidence from fieldwork in Vidarbha suggest that asymmetries revealed in this analysis may be linked to trader's market power and inadequate market information among farmers.     

Optimal Storage by Crop Producers

When post–harvest marketing strategies are restricted by disallowing speculative purchases, sales out of storage becomes an irreversible decision and the dynamic marketing problem becomes analogous to the optimal exercise of a financial option. The optimal marketing strategy is to hold at low prices and to sell at high prices with a cutoff price function marking the boundary between low and high prices. A method for estimating the cut–off price function is developed and applied to Illinois soybean prices. The decision rule is demonstrated to result in substantial gains from storage.     

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.     

Inter‐ and intra‐seasonal crop acreage response to international food prices and implications of volatility

Understanding how producers make decisions to allot acreage among crops and how decisions about land use are affected by changes in prices and their volatility is fundamental for predicting the supply of staple crops and, hence, assessing the global food supply situation. This study makes estimations of monthly (i.e., seasonal) versus annual global acreage response models for the world's principal staple food crops: wheat, corn, soybeans, and rice. Primary emphasis is given to the magnitude and speed of the allocation process. Estimation of intra‐annual acreage elasticity is crucial for expected food supply and for input demand, especially in the light of the recent short‐term volatility in food prices. The econometric results indicate that global crop acreage responds to crop prices and price risks, input costs as well as a time trend. Depending on respective crop, short‐run elasticities are about 0.05 to 0.40; price volatility tends to reduce acreage for some of the crops; comparison of the annual and the monthly acreage response elasticities suggests that acreage adjusts seasonally around the globe to new information and expectations. Given the seasonality of agriculture, time is of an essence for acreage response. The analysis indicates that acreage allocation is more sensitive to prices in the northern hemisphere spring than in winter and the response varies across months.     

Implications of high food prices for poverty in Pakistan

The study estimates the impacts of rising world food prices on poverty in rural and urban areas of Pakistan. Household income and expenditure data for 2004/2005 is used to estimate compensated and uncompensated price and expenditure elasticities using the linear approximation of the almost ideal demand system. Taking the unexpected component of higher domestic food prices in 2007/2008, own and cross price compensated elasticities are used to derive the changes in the quantity consumed, food expenditure and impacts on poverty assuming the food crisis happened in 2004/2005. The results indicate that poverty increased by 34.8%, severely affecting the urban areas where poverty increased by 44.6% as compared to 32.5% in rural areas. The estimates show that 2.3 million people are unable to reach even one‐half of poverty line expenditures while another 13.7 million are just below and 23.9 million are just above the poverty line. In the short run, it is important to ensure food availability to these people. In the long run, the policy environment of subsidizing urban food consumers by keeping wheat prices lower than the international price, needs to be reconsidered to provide the right incentives to increase food availability.     

The price stabilization effects of the EU entry price scheme for fruit and vegetables

The article assesses the stabilization effects of the EU import regime for fresh fruit and vegetables based on the entry price system (EPS). The analysis is carried out on the EU prices of tomatoes and lemons and those of imports from some of the main competing countries on the EU domestic markets: Morocco, Argentina, and Turkey. It is based on the estimation of a threshold vector autoregressive econometric model that is shown capable of taking the workings of the import regime into account. The model shows that prices behave differently when import prices are above/below the trigger entry price. This article allowed to highlight the cases for which the isolation effect of EPS seems reached and the resulting stabilization effects.     

The Spatial Integration of Paddy Markets in Vietnam

This paper examines whether there is spatial integration between and within paddy markets in the north and south of Vietnam. The empirical model developed uses estimates of transfer costs to generalise Ravallion's model of spatial market integration to allow for threshold effects. A sequential testing strategy is used to test for market segmentation, the number of thresholds, long‐run integration, informational efficiency and the Law of One Price within an error‐correction framework. We find neither threshold effects nor weak evidence of paddy market integration between northern and southern Vietnam. There is, however, evidence of both threshold effects and stronger market integration within the Red and Mekong River deltas. Whenever price spreads exceed their thresholds, at least 60% of price changes are transmitted between regional markets within a month. Nonetheless, the instantaneous version of the Law of One Price only holds for a few regimes and market pairs. These results suggest that national level policies cannot be relied upon to stabilise or support paddy prices in Vietnam. Instead, policies need to be designed with the specific production, consumption and marketing characteristics of northern and southern Vietnam in mind.     

The effects of NCPB marketing policies on maize market prices in Kenya

The Government of Kenya pursues maize marketing policy objectives through the National Cereals and Produce Board (NCPB), which procures and sells maize at administratively determined prices, and stores maize as a contingency against future shortages. A private sector marketing channel competes with the NCPB. This article estimates the effects of NCPB activities on the historical path of private sector prices in Kenyan maize markets between 1989 and 2004. The analysis is carried out using a reduced form vector autoregression model (VAR) estimated with sparse data and imposing only minimal identification restrictions. Results show that NCPB activities have stabilized maize market prices in Kenya, reduced price levels in the early 1990s, and raised average price levels by roughly 20% between 1995 and 2004. Over the past decade, the price-raising activities of the NCPB have transferred income from urban consumers and a majority of small-scale farm households that are net buyers of maize to a relatively small number of large- and small-scale farmers who are sellers of maize.     

How much of commodity price behavior can a rational expectations storage model explain?

A rational expectations competitive storage model was applied to the U.S. corn market, to assess the aptness of this framework in explaining monthly price behavior in an actual commodity market. Relative to previous models, extensive realism was added to the model, in terms of how production activities and storage costs are specified. By modeling convenience yield, “backwardation” in prices between crop years did not depend on the unrealistic assumption of zero ending stocks. Our model generated cash prices that were distributed with positive skewness and kurtosis, and mean and variance that increased over the storage season, comparable to the persistence and the occasional spikes observed in commodity prices. Futures prices were generated as conditional expectations of cash prices at contract maturity, and the variances of futures prices exhibited realistic time–to‐maturity and seasonal patterns. Model realizations of cash and futures prices over many “years” were used to demonstrate the wide variety of price behaviors that could be observed in an efficient market with a similar market structure, implying that economic and policy implications drawn from short, historical samples of prices could be misleading.     

Threshold cointegration and spatial price transmission when expectations matter

We examine the performance of the threshold cointegration approach, specifically Band‐TVECM, to price transmission analysis in an explicit context where trade decisions are made based on expectation of final prices, because trade takes time. We find that, following a standard inference strategy, a large portion of three‐regime cases are not identified as such. Results show that transfer costs are systematically underestimated, particularly in three‐regime models. The speed of price transmission is also biased in three‐regime models. Furthermore, inferences about occurrence of trade are poor, with estimated models suggesting far lower market integration than is true in the data‐generating process.     

Determination of the international maize price: What is the growing role of Brazil and Ukraine?

This paper examines the relationships among maize prices for four countries to determine if newly emerging exporters, Brazil and Ukraine, influence the international price of maize. Our work focuses on each market's participation in the price discovery process rather than trying to determine a price leader. We find that the United States plays the largest role in price discovery, followed by Argentina, Brazil, and Ukraine. We also search for export thresholds and find that Ukraine's contribution to price discovery rises slightly when an export threshold of 2.3 million tons is reached. No export thresholds were found for Brazil. Export thresholds for Argentina were found but only have a minor impact on price relationships. We also found that price relationships vary considerably across seasons of the year.     

Spatial integration between Finnish and Dutch potato markets

This study estimated a conditional mean model for producer prices of fresh potatoes in Finland and for wholesale selling prices of fresh potatoes in the Netherlands. Unit roots were tested in the Finnish and Dutch price series. Then, an asymmetric error correction model with thresholds was estimated for potato prices between Finland and the Netherlands. Asymmetry was allowed both in short and long-run price transmission. The results suggest that the prices are cointegrated and the arbitrage system is functioning, but with a significant time lag between the Finnish and Dutch potato markets. The price response is also asymmetric in that the Finnish price moves towards a steady state equilibrium faster from above than from below the equilibrium.     

Nonlinear adjustments in deviations from the law of one price for wholesale hog prices

This article applies the Band‐Threshold Autoregression (Band‐TAR) model to investigate whether the law of one price (LOOP) holds in Taiwanese wholesale hog markets during the period from May 1987 through December 2003. We find evidence of a nonlinear mean reversion in deviations from the LOOP for relative hog prices. Our empirical study confirms the presence of thresholds and provides strong evidence in support of the view that the regional hog markets have been tightly integrated in Taiwan and that the wholesale hog market in Taiwan is an efficient market economy. Furthermore, the estimated half‐lives from the nonlinear generalized impulse response analysis are as short as four months.     

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.     

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.     

Testing vertical price transmission for Vietnam's Robusta coffee

Vietnam has undergone market reforms over the last three decades; and as a consequence, the coffee sector has become increasingly market‐driven. The success of the government's liberalisation policies in terms of market efficiency is investigated by examining the transmission of both positive and negative price changes for Robusta coffee between export and farmgate prices. We used a threshold vector error correction model and high‐frequency daily data. The primary result here is that of a symmetric price transmission between export and farm‐level prices. This result holds when tested with weekly price data, derived from the daily data. Farmgate prices respond faster to decreases than increases in export prices when the long‐run deviation exceeds a certain threshold. These price changes are transmitted within several days. This research also confirms the importance of transaction costs, and other price frictions mostly ignored in prior analyses for coffee.