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.     

Dynamics of Beef Supply in the Presence of Cointegration: A New Test of the Backward-Bending Hypothesis

Following a general-to-specific strategy of model development, we develop error-correction equations for fed beef supply and feeder cattle demand. Starting with a theoretically acceptable set of variables, preliminary tests for unit roots and cointegrating vectors show stationary quantity variables and cointegrated prices. Simplification of the lag structure leads to equations with considerably richer dynamics than in previous studies. The final model passes several misspecification tests, is robust when estimated on subsamples of data, and makes more accurate out-of-sample forecasts than other models. In beef supply, the estimated error-correction model decomposes the backward-bending supply hypothesis into negative short-run and positive long-run supply elasticities at the monthly frequency.     

Advertising Expenditures and the Consumption of Alcoholic Beverages

The theory of consumer behavior is applied to the estimation of a demand svstem. Monthly data on alcoholic beverages (beer, wine, liquor, soft dhnks) from the province of Ontario in Canada are analyzed. Before estimating the linear approximate almost ideal demand system (LA/AIDS), unit root and cointegration tests are implemented. Budget shares, per capita advertising expenditures, real total expenditure, prices and per capita consumption are found to be non-stationary. The budget share, the advertising expenditures, the prices and the real total expenditure are cointegrated for each beverage. Own and cross-price elasticities, income elasticities and own and cross-advertising elasticities are calculated from the estimated or the demand system. Based on own-price elasticities and income elasticities, alcohol consumption is consistent with the law of demand and the products analyzed are normal goods. The estimation of income and advertising effects is important for analyzing the need for, and the effectiveness of, potential control policies. The advertising elasticities are small but statistically significant. This suggests that advertising may promote alcoholic beverage consumption. The estimated inelastic demands for beer and wine suggest that the primary purpose of high excise taxes levied by the Federal and Provincial governments is to raise government revenues and not to discourage consumption.     

When the theory is not enough - valuation of forest resources with “efficiency” prices in practice

In resource accounting, simple theoretical models built upon efficiency prices have been developed to capture changes in social welfare generated by natural resources. We examine whether changes in market stumpage prices, as proxies for efficiency prices, have actually reflected changes in the physical timber inventories in Finland and Sweden during the past seventy years. Cointegration and unit root tests show that no long-term equilibrium relationships exist between the timber prices and stocks. After identifying a potential reason for the result, the basic theoretical growth model is slightly elaborated to provide a more appropriate framework for measuring net domestic product for the forest sector.     

Do rice prices follow a random walk? Evidence from Markov switching unit root tests for Asian markets

This study revisits the issue of mean reversion in the import rice prices of six Asian countries over the period between 1995 and 2015. Augmented Dickey Fuller tests with a conventional linear regression model support the presence of a unit root in the levels of the price data. However, when regressions allow for Markov switching in coefficients and variances to capture periodic shifts in levels and volatilities, there is strong evidence against the unit‐root null hypothesis in favor of stationarity over much of the observation period.     

Long‐Run Drift,Co‐Movement and Persistence in Real Wheat and Maize Prices

Trends in real prices for food commodities are both important and controversial. Paying particular attention to issues of methodology, this paper assesses the evidence for a downward drift in the real prices of wheat and maize. It is found that the apparent strength of that evidence depends substantially on whether the time series generating models are taken to be trend‐stationary or difference‐stationary, and on whether allowance is made, through incorporation of dummy variables in the models, for events in one or two extreme years. Once dummy variables are incorporated, we find little evidence against difference‐stationarity. The analysis then proceeds, through tests for cointegration, to the construction of error‐correction models linking the two prices and to the estimation of persistence of shocks in this bivariate framework. The paper presents modest evidence for downward drift in real grain prices of about 1 to 1.5 per cent per annum, shows that wheat and maize prices cointegrate and estimates that direct and cross‐persistence measures take values of less than unity.     

How convergent are rice export prices in the international market?

This study revisits the issue of long-term price convergence of rice export prices for India, Pakistan, Thailand, Uruguay, the United States, and Vietnam using a two-stage pairwise unit root testing approach. To deduce evidence or lack of proof of convergence in price series, we also examine convergence using sigma and beta convergence specified in both unconditional and conditional frameworks. The methodology used is driven by the need to address three key concerns: (i) the likelihood of finding stationary price differentials, (ii) the magnitude of these differentials, and (iii) their speed of adjustment. To evaluate these concerns, we use monthly data for 18 price series drawn from these six countries from September 2011 to February 2021. The evidence points to a lack of international convergence. This gives rise to the possibility that a shield from a general downward export price trend is already in place for some exporters. Furthermore, we find that the likelihood of convergence is greater between pairs of price series that are characterized as high quality or having the same country of origin or having similar market share. Evidence also suggests that a converged pairing is more likely to have a smaller price differential if both price series are for low-quality rice.     

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.     

Testing for regional convergence of agricultural land prices

The focus of this paper is on spatial market integration in agricultural land markets. We scrutinize the applicability of the law of one price to land markets and distinguish between absolute and relative versions of this “law”. Panel data unit root and stationarity tests are applied to land sale prices in the German state Lower Saxony. Three main clusters with different price developments are detected. Our results indicate that the law of one price holds only locally due to structural differences among regions.     

Farmland prices, structural breaks and panel data

Previous time series evidence has indicated that farmland pricesand cash rents are not cointegrated, a finding at odds withthe present value model of farmland prices. We argue that thisfailure to find cointegration may be due to low power of testsand to the presence of structural change representing a shiftingrisk premium on farmland investments. To accommodate this possibility,we use panel unit root and cointegration methods that are morepowerful than conventional time series methods and allow forbreaks in the cointegration relationship. Our results, basedon a large panel covering 31 US states between 1960 and 2000,suggest that the present value model of farmland prices cannotbe rejected.     

Is Exchange Rate Pass-Through in Pork Meat Export Prices Constrained by the Supply of Live Hogs?

The impact of lags in the production and marketing of agricultural products on the degree of exchange rate pass-through in export prices is investigated. The predictions of the theoretical model are tested by investigating Canadian pork export prices in the United States and Japan. The empirical methodology accounts for unit root and cointegration using the dynamic seemingly unrelated regression framework and a minimum distance estimator. Predetermined hog supplies have a statistically significant impact on export prices of two out of three Canadian provinces. The degree of misspecification involved with standard pass-through models that do not account for production lags is also illustrated.     

Growth and the Environment in Canada: An Empirical Analysis

Standard reduced-form models are estimated for Canada to examine the relationships between real per capita gross domestic product and four measures of environmental degradation. Of the four chosen measures of environmental degradation, only concentrations of carbon monoxide appear to decline in the long run with increases in real per capita income. The data are also tested for the presence of unit roots and for the existence of cointegration between each of the measures of environmental degradation and per capita income. ADF and Phillips-Perron tests indicate unit roots in the logs of the measures of all variables. The Engle-Granger test and Johansen's maximum eigenvalue test suggest that a long-term relationship between per capita income and the measures of environmental degradation does not exist. Causality tests also indicate bidirectional causality, not unidirectional causality, from income to the environment. The results suggest that Canada does not have the luxury of being able to grow out of its environmental problems. The implication is that to prevent further environmental degradation, Canada requires concerted policies and incentives to reduce pollution intensity per unit of output across sectors, to shift from more to less pollution-producing outputs and to lower the environmental damage associated with aggregate consumption.     

Deregulation of the Australian Wheat Export Market: What Happened to Wheat Prices?

ABSTRACT

This report investigates whether deregulation of the Australian wheat export market induced a structural change in the price data generation process. We analyze the unit root properties of Western Australian wheat price series by testing for the possibility of single and double structural breaks. Daily spot prices for the period of May 20, 2003, to September 14, 2010 are used. We find the wheat price series has a unit root with two structural breaks but neither breaks coincides with the time when the Wheat Export Marketing Act 2008 came into effect on July 1, 2008. The implication of our results is that deregulation was not the main cause of structural breaks in the price series in the sample period.     

Dynamics of rice prices and agricultural wages in the Philippines

Rice trade liberalization in the Philippines should decrease domestic rice prices impacting both agricultural wages and the welfare of agricultural wage earners. This study examines the short-run and long-run relationship between rice prices and agricultural wages in the Philippines using a neoclassical wage determination model. Three empirical frameworks are used—a cointegration/error correction framework, which assumes nonstationary variables in long-run equilibrium, a first difference model that assumes nonstationary variables but no long-run equilibrium, and an OLS framework that assumes the model variables are stationary. Conclusions are reasonably robust across the three empirical frameworks with wages adjusting positively to rice price changes with a short-run elasticity of 0.29 to 0.57, and a long-run elasticity of 0.70 to 1.0 in preferred models. An analysis of welfare implications suggests that although households that are heavily reliant on agricultural wages for income will be adversely affected by rice price decreases, other households will benefit.     

Do Forest Products Prices Display Long Memory?

The behavior of forest products prices has large implications for forest management and policy. Decisions such as the timing of harvesting and investment in new plantations depend on future price expectations and policy makers often are concerned about the persistence of price shocks for stabilization purposes. Previous research on the topic has been mixed and focused on the question of whether prices are integrated of order one (i.e., have a unit root) and are nonstationary or if they are integrated of order zero and are stationary and mean‐reverting. In an effort to understand the price process for two key forest products (lumber and pulp), time‐series tests were applied to over 40 years of monthly pricing data. Using a modified Dickey–Fuller test, we rejected the null hypothesis of a unit root on most series. However, a separate test also soundly rejected a stationary null hypothesis. Such a finding led us to test whether forest products prices are fractionally integrated, exhibiting long memory. Estimates of the memory parameter (d) for various lumber price series ranged between 0.68 and 0.81 and for pulp it was 0.64. This implies that prices are both mean‐reverting (in the sense that shocks die out) and nonstationary. Le comportement des prix des produits forestiers a d’importantes répercussions sur la gestion et la politique forestières. Certaines décisions, telles que le choix du moment de la récolte et les investissements dans de nouvelles plantations, dépendent des anticipations quant aux prix futurs et, souvent, les décideurs sont préoccupés par la persistance des chocs de prix pour des raisons de stabilisation. Les travaux de recherche antérieurs ont été variés et visaient à déterminer si les prix étaient intégrés de l’ordre  1 (c.‐à‐d. avec une racine unitaire) et non stationnaires ou s’ils étaient intégrés de l’ordre 0, stationnaires, avec une tendance au retour à la moyenne. Afin de comprendre le processus de prix de deux  produits forestiers clés (bois d’?uvre et pâte), nous avons effectué une analyse de séries chronologiques comprenant des données de prix mensuelles recueillies sur une période de plus de 40  ans. À l’aide d’un test de Dickey‐Fuller modifié, nous avons rejeté l’hypothèse nulle de la présence d’une racine unitaire dans la plupart des séries. Un autre test a également permis de rejeter sans équivoque l’hypothèse nulle de stationnarité. Ces résultats nous ont amenés à vérifier si les prix des produits forestiers étaient fractionnellement intégrés et présentaient une mémoire longue. Les estimations du paramètre de mémoire (d) de diverses séries de prix variaient de 0,68 à 0,81 pour le bois d’?uvre et s’établissaient à 0,64 pour la pâte. Ces résultats autorisent à penser que les prix ont une tendance au retour à la moyenne (dans le sens où les chocs disparaissent) et qu’ils sont non stationnaires.     

Pricing to Market Behavior by Canadian and U.S. Agri-food Exporters: Evidence from Wheat, Pulse and Apples

A fixed-effects model to control for time variation in marginal costs is employed to pinpoint evidence of price discriminatory behavior of Canadian and U.S. exporters of agri-food products. We test for evidence of pricing to market behavior and whether price discrimination or commodity/country characteristics may provide a plausible explanation. A distinguishing feature of our approach is to examine the time-series properties of the data by the conventional augmented Dickey-Fuller and recently developed panel unit root test. The panel data set employed in this paper consists of annual exchange rates and export prices for three agri-food products (wheat, pulse and apples) exported by Canada and the U.S. in foreign markets during 1980–98. Our fixed-effects model suggests that U.S. exporters are sensitive to exchange rate changes, while Canadian exporters in most cases raised price markups in response to a depreciated currency in overseas markets. The results highlight the differences in pricing policy that both countries employ to merchandise agri-food products in export markets.     

Opportunities for Commercial Hemp Production

Hemp production has been nonexistent in the United States since the 1950s. However, low prices for traditional crops have peeked interest in commercial hemp production. The current literature on hemp suggests that it may compete on the margin with traditional crops, but is not likely to generate sizeable profits. Hemp appears slightly more profitable than traditional row crops, but less profitable than other specialty crops. An important constraint to a viable commercial hemp industry is the current state of harvesting and processing technologies, which are quite labor intensive, and result in relatively high per unit costs.     

The Demand for Food Quality in Rural China

Many studies of food demand do not use actual prices but unit values, obtained by dividing expenditures by the quantity consumed. This can bias empirical analyses because unit values are not exogenous market prices; they reflect household food quality choices within each food category. This article develops a framework for assessing the resulting bias in income and price elasticities of demand and applies the framework to data for rural China. Empirical results indicate that households in rural China tend to consume higher-quality food as income increases, with a greater sensitivity to income for basic foods than for luxury foods.     

Food Competition in World Markets: Some Evidence from a Panel Data Analysis of Top Exporting Countries

This paper investigates the relevance of relative prices and world income as determinants of food exports for the top trading countries in the period 1992–2012 using a panel data framework. We find that price elasticities generally take lower values for processed goods, and the opposite holds for income elasticities. Processed goods are also characterised by an inverse relationship between price elasticities and average unit values. The analysis suggests that both emerging and advanced countries can be expected to increase their export specialisation in processed goods. Furthermore, developed economies can face fierce competition from emerging countries by enhancing the quality content of their processed good exports.     

A Nonparametric Test of the Traditional Travel Cost Model

The traditional travel cost model operates on the assumption that choices are made regarding the number of trips to various sites over an entire recreation season. This paper uses actual recreation data to test the consistency of this model with postulates of rational economic choice as embodied in the axioms of revealed preference. The paper assumes consumer rationality and examines the effects of alternative trip prices and model structures on the degree of consistency between them and the axioms of choice. Using tests developed by Varian and Tsur, the authors find that site choices at prices proxied by travel costs for most individuals in the sample violate the axioms. The violations are quite large when time costs, both in traveling and on-site, are omitted from the prices. When they are included, violations are almost as numerous, but not as large. The paper also examines demand heterogeneity by stratifying the sample and repeating the nonparametric tests. These findings suggest caution be used in interpreting welfare measures derived from traditional travel cost models, especially those that do not include measures of time value. The authors' approach provides a method for screening travel cost data and preparing for model selection and estimation.