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.     

The New Tomato Suspension Agreement: What Are the Implications for Trade Flows?

This paper examines the implications of the new tomato suspension agreement (signed on March 4, 2013, by the U.S. government and Mexican tomato producers) for trade in fresh tomatoes and processed tomato products. The empirical analysis is performed through a gravity model that accounts for vertical linkages between primary and processed goods. The estimated gravity parameters are used to implement suspension agreement scenarios. The results show that the new suspension agreement leads to considerable decreases in Mexico's exports of fresh tomatoes to the United States. These decreases are accompanied with various trade diversion and deflection effects. There are increases in Mexico's exports of processed tomato products to the United States and other countries, and in Mexico's exports of fresh tomatoes to non‐U.S. destinations. These increases do not amount, however, to considerable compensations of the decreases in Mexico's fresh tomato exports to the United States. The results also suggest that the initial 1996‐based suspension agreement has significantly smaller impacts on trade flows over the period that preceded the implementation of the new suspension agreement.     

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.     

Rural Chile Transformed: Lights and Shadows

Rural society in Chile has undergone profound change over the past few decades. For centuries, large haciendas had dominated Chile's Central Valley. The agrarian reforms carried out by Frei and Allende – and to a greater extent the counter‐reform of Pinochet – transformed that property structure with its generalized system of agricultural production for the domestic market. Recently, there has been a marked shift in emphasis towards specialization, exports and off‐farm agricultural resources. A seasonal labour market has arisen, employing predominantly female workers, whose precarious work conditions stand in marked contrast to the success of Chilean agricultural exports. This paper reviews the main trends in Chilean agriculture and rural society, drawing on data gathered principally in Colchagua Province, which is known for its fine export wines.     

Intra-annual sheep price patterns and factors underlying price variations in the central highlands of Ethiopia

A sheep market survey was undertaken to determine the effects of certain animal and market characteristics on price and the pattern of sheep prices in relation to seasons. Nine key Ethiopian central highlands markets were surveyed for a period of one year in 1989. Each market was surveyed once a week on the main market day. Price, weight, sex, age, colour, condition score, breed type and buyer's purpose were recorded for all completed transactions as well as the numbers offered and sold on each market day. A total of 50062 cases were recorded. Three markets, each representing redistributive, intermediate and terminal markets, as identified by the distribution in buyer's purpose were chosen for further analysis. Considerable weekly price variation was evident in these markets. Prices were also seasonal with higher premiums paid during some religious festivals. Animal characteristics (weight, age, condition, sex, colour) as well as buyer's purpose and seasons were variably important in explaining variation in price among animals within weeks. Variations in the composition of these characteristics from week-to-wcek were among factors underlying changes in weekly mean prices. R² varied from 0.2659 to 0.3583 in the quadratic price per kg model and from 0.7822 to 0.8413 in the quadratic price per head model in the three markets. However, it was found that price per head was predicted equally well overall by estimated price per kg multiplied by actual weights and that because of wide variation in weights, both within and between weeks, price per kg is more useful market information.     

Price Discrimination in Russian Wheat Exports: Evidence from Firm‐level Data

Russia emerged as an important wheat exporter in recent years raising the question of how this will affect international wheat markets. In particular developing countries – the main destination of Russian wheat exports – could be harmed by aggressive pricing behaviour. This article analyses the exertion of price discrimination by Russian wheat exporting firms based on Krugman's pricing‐to‐market hypothesis. We apply Knetter's panel model to a firm‐level dataset and find evidence for price‐discriminating behaviour by Russian firms in 25 out of 61 destination countries over the period 2002–2011.     

A STUDY OF BANANA SUPPLY AND PRICE PATTERNS ON THE SYDNEY WHOLESALE MARKET: AN APPLICATION OF SPECTRAL ANALYSIS*

Spectral analysis is applied to weekly supply and price series for bananas traded on the Sydney wholesale market. Many interesting features are revealed such as the pronounced seasonal component and the two week lag structure between the supply and price series. These results are discussed in relation to the known behaviour of the market and some implications for marketing decisions are tentatively drawn.     

A structural time series analysis of US broiler exports

A structural time series model is used to determine the dynamic characteristics, forecasting properties, and policy implications of factors affecting the US broiler export market. The emphasis is on international market responsiveness. The analysis indicates that in addition to the explanatory variables a trend component has been vital in the expansion of the broiler industry during the study period. The results indicate that export markets are more price responsive than the domestic markets, that interventions in the Canadian and Mexican markets reduce their imports, and exchange rate changes have significant impacts on US exports.     

中国鲜切花出口:市场规模、市场分布与竞争力效应

本文利用联合国贸易署的数据,采用市场集中度和修正后的恒定市场份额模型,分析1992—2009年中国鲜切花出口的格局变化及出口波动情况,并分阶段从动态的视角分析影响中国鲜切花出口增长的原因。研究表明,中国鲜切花出口的市场集中度在17年的时间跨度里呈现出分散的趋势,中国鲜切花出口额自2001年以来的持续快速增长,是由于国际鲜切花进口需求增长、市场分布效应和竞争力提高等因素共同发挥作用造成的,其中中国鲜切花竞争力的提升成为促进中国鲜切花出口额增加的最重要原因。     

西宁近48a来气温变化的多时间尺度分析

利用Morlet小波分析了1954￣2001年西宁市年平均气温距平时间序列的小波变化特征,揭示了气温变化的多时间尺度结构,分析了其中存在的主要周期振荡和突变点,并与功率谱分析结果进行比较。结果表明:西宁市年平均气温存在多时间尺度的周期变化特征,西宁市年平均气温存在3.5a,准11a和准24a的主周期。西宁市的气温变化存在着明显的多时间尺度,即年代际尺度和年际尺度的周期性变化,20￣32a时间尺度具全域性外,其它尺度的局部化特征则很强。西宁市的气温变化还显示出突变点分布和及其位相结构。21世纪初西宁市年均气温还将处在一个偏冷期。通过功率谱和小波变换方法在诊断气温变化上的应用,得出功率谱在诊断气温变化中一些缺点,而小波变换方法能分析气温序列随时间变化的多层次结构,功率谱分析方法由于自身原因难以做到这一点。     

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.     

The role of the U.S. exchange-rate equity market volatility on agricultural exports and forecasts

This article estimates the U.S. state-level soybean export forecast until December 2024 using a seasonal autoregressive integrated moving average (SARIMA) model. We utilize the newly developed exchange-rate equity market volatility (EMV-EX) to improve model fit and the Dirichlet process mixture model (DPMM) to control for unobserved heterogeneity. Using monthly data from January 2004 to December 2020, the study shows that soybean exports for states without ports are underestimated at the expense of states with ports. The EMV-EX has a positive effect on soybean exports. The forecasts reveal no expected changes in the trends for soybean exports until December 2024. This study's results are useful to make and to implement more informed policy decisions for risk-mitigating strategies such as the market-facilitation program.     

Time‐varying Hedge Ratios: A Principal‐agent Approach

We use the classic agency model to derive a time‐varying optimal hedge ratio for low‐frequency time‐series data: the type of data used by crop farmers when deciding about production and about their hedging strategy. Rooted in the classic agency framework, the proposed hedge ratio reflects the context of both the crop farmer's decision and the crop farmer's contractual relationships in the marketing channel. An empirical illustration of the Dutch ware potato sector and its futures market in Amsterdam over the period 1971–2003 reveals that the time‐varying optimal hedge ratio decreased from 0.34 in 1971 to 0.24 in 2003. The hedging effectiveness, according to this ratio, is 39%. These estimates conform better with farmers’ interest in using futures contracts for hedging purposes than the much higher estimates obtained when price risk minimisation is the only objective considered.     

West and Central African iron ore development and its impact on world prices

The focus of the paper is on the potential of iron ore supplies from West and Central Africa to enter the export market over the short and medium terms and how this could impact the supply‐side capacity and market price. To assess this, three export development scenarios (low, medium and high risk) are constructed for 17 iron ore mines (over 27 production expansion projects) in West and Central Africa. The projections for African iron ore are compared with the latest medium‐term import forecasts and suggest that the development of West and Central African iron ore has the potential to create significant downward pressure on the price of iron ore exports over the medium term. The increased export capacity could push marginal producers – mainly in China but also in India and elsewhere – out of the market.     

Cotton market integration and the impact of China's new exchange rate regime

This article studies the integration of China's cotton market with the international market, especially the U.S. market. Investigating the futures prices from the Intercontinental Exchange (ICE) in the U.S. and the Zhengzhou Commodity Exchange (ZCE) in China with several time series models, we find that a long‐run cointegration relationship exists between these two series. The two markets share price transmissions, and based on results from an Autoregressive Conditional Heteroskedasticity (ARCH) model, we find their price volatilities are similar. We argue that China's recent exchange rate reform and its gradual liberalization in bilateral cotton trade since it joined World Trade Organization have had important impacts on these futures markets. Based on these findings, several important economic and policy implications are derived.     

Sense and sustainability revisited: the limits of total factor productivity measures of sustainable agricultural systems

Many economists have advocated and applied total social factor productivity (TSFP) (i.e., total factor productivity estimated with both market and non‐market inputs and externalities, and with all factors valued at social prices) as a single all‐embracing measure of agricultural sustainability. This paper reviews the conceptual and practical issues in measuring TSFP and shows that no one measure alone will be theoretically or empirically robust as an indicator of sustainability. TSFP is a conceptually flawed measure since inclusion of non‐market inputs and outputs and social price‐based valuation, in most cases, violates the theoretical basis underlying those estimates. Trends in TSFP also have limited value in diagnosing the nature of sustainability problems, unless changes in productivity are related to underlying changes in technology, human and physical infrastructure, and indicators of resource quality. More attention needs to be given to defining key indicators of agro‐ecosystem health and relating these measures to trends in productivity. This analysis must be sufficiently disaggregated and for a long enough time period to allow for spatial and temporal variability inherent in agricultural production. Secondary data at the district level on both conventional inputs and outputs and resource quality have recently allowed more quantitative estimates of sustainability and its causes. With limited data, yield growth decomposition analysis can often be used to provide valuable insights into sustainability problems. Meanwhile, there is a need to invest in long‐term experimental and panel surveys of farmers and their fields for key production systems in order to provide long‐term data that will allow full productivity accounting, using more formal statistical procedures. Regardless of the approach selected, the findings of this paper strongly suggest a need for economists, agronomists and soil scientists to collaborate in integrating approaches in order to provide more robust and informative measures of sustainability.     

Market Integration and Market Efficiency under Seasonal Tariff Rate Quotas

Switzerland applies seasonal tariff rate quotas (TRQs) for the import of many fruits and vegetables during the domestic harvest season. We examine how this system affects the relationship between Italian and Swiss tomato prices and test for physical market integration and spatial equilibrium conditions over time. We use detailed, transaction‐based data on trade flows and trade costs and estimate an extended parity bounds model, following Barrett and Li (2002). We confirm that in the summer season, when TRQs are in place, markets are inefficient. While quota holders receive positive rents, the marginal rents for importers without quota shares are negative. This inhibits trade flows above the in‐quota import quantity allowed by TRQs. Hence, despite leading to inefficiencies and creating rents for importers, seasonal TRQs are effective in protecting domestic production against competing imports.     

Agricultural price transmission across space and commodities during price bubbles

This article investigates agricultural price transmission during price bubbles. The empirical approach concerns the horizontal transmission of cereal prices both across different market places and across different commodities. The trade policy intervention put forward to mitigate the impact of price exuberance is considered. The analysis is performed using Italian and international weekly spot (cash) price data over years 2006–2010, a period of generalized turbulence of agricultural markets. Firstly, the properties of price time series are explored; then, interdependence across prices is specified and estimated by adopting appropriate cointegration techniques. Results suggest that the bubble had only a slight impact on the price spread and the temporary trade‐policy measure, when effective, has limited this impact.     

Agricultural Exports and Economic Growth in Developing Countries: A Panel Cointegration Approach

This paper quantifies the contribution of agricultural exports to economic growth in developing countries. We estimate the relationship between GDP and agricultural and non‐agricultural exports for 42 countries using panel cointegration methods. Results show that a long‐run relationship exists, the agricultural export elasticity of GDP is 0.07 whereas that of non‐agricultural exports is 0.13, and total exports Granger‐cause GDP, which supports the export‐led growth hypothesis. Structural differences exist in the relationship by broad income group. Balanced export‐promotion polices are implied for the poorest countries, but, for those with higher incomes, higher economic growth is achieved from non‐agricultural exports.     

Australian wine industry competitiveness: why so slow to emerge?

Despite favourable growing conditions, Australia's production or exports of wine did not become significant until the 1890s. Both grew in the 1920s, but only because of government support. Once that support was removed in the late 1940s, production plateaued and exports diminished: only two per cent of wine production was exported during 1975–1985. Yet over the next two decades, Australia's wine production quadrupled and the share exported rose to two‐thirds – before falling somewhat in the next 10 years. This paper explains why it took so long for Australia's production and competitive advantage in wine to emerge, why it took off spectacularly after the mid‐1980s and why it fell in the 10 years to 2016. It concludes that despite the recent downturn in the industry's fortunes, the country's international competitiveness is now firmly established and commensurate with its ideal wine‐growing climate, notwithstanding the likelihood of further boom‐slump cycles in the decades ahead.