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2020, American Journal of Agricultural Economics
https://doi.org/10.1002/AJAE.12088…
22 pages
1 file
Energy represents an important share of production costs for many agricultural commodities. Previous studies have found mixed evidence of a pass-through relationship between oil prices and agricultural commodity prices, a relationship that has the potential to disrupt farm-level decision making. We propose that these mixed findings are in part due to heterogeneity in the pass-through relationship across time horizons. We use a new wavelet-based regression approach to explore horizon-based heterogeneity in the relationship between oil and agricultural commodity prices. We find strong evidence of heterogeneity across time horizons and commodities. We develop a stylized model of agricultural production and show that agricultural contracts can generate price stickiness that leads to heterogeneity in input price pass through over different horizons. We also find evidence that recent technological shifts have led to a structural change in this horizon-based heterogeneity.
American Journal of Agricultural Economics, 2020
Energy represents an important share of production costs for many agricultural commodities. Previous studies have found mixed evidence of a pass‐through relationship between oil prices and agricultural commodity prices, a relationship that has the potential to disrupt farm‐level decision making. We propose that these mixed findings are in part due to heterogeneity in the pass‐through relationship across time horizons. We use a new wavelet‐based regression approach to explore horizon‐based heterogeneity in the relationship between oil and agricultural commodity prices. We find strong evidence of heterogeneity across time horizons and commodities. We develop a stylized model of agricultural production and show that agricultural contracts can generate price stickiness that leads to heterogeneity in input price pass through over different horizons. We also find evidence that recent technological shifts have led to a structural change in this horizon‐based heterogeneity.
2019
The connection between energy and agricultural commodity prices have been the subject of frequent debate, especially with the introduction of biofuel policies that incentivize the substitution of gasoline and diesel for corn ethanol and other biofuels derived from agricultural feedstocks. To properly isolate the impact of biofuel policy from commensurate business cycle fluctuations, it is crucial to understand the heterogeneity in horizon-based effects—a deficit that we rectify with a novel mixed-domain econometric approach utilizing wavelet methods. We find empirical evidence suggesting a strengthening of oil price pass through to select agricultural commodities, most notably corn. Our empirical results are substantiated with a stylized theoretical model that explains how the structure of marketing and production contracts contribute to the differential pass through results across commodities.
2021
In this article we analyse the oil-food price co-movement and its determinants in both time and frequency domains, using the wavelet analysis approach. Our results show that the significant local correlation between food and oil is only apparent. This is mainly due to the activity of commodity index investments and, to a lower extent, to the increasing demand from emerging economies. Furthermore, we employ the wavelet entropy to assess the predictability of the time series under consideration. We find that some variables share with both food and oil a similar predictability structure. These variables are those that mostly co-move with both oil and food. Some policy implications can be derived from our results, the most relevant being that the activity of commodity index investments is able to increase correlation between food and oil. This activity generates highly integrated markets and an increasing risk of joint price movements which is potentially dangerous in periods of economi...
Complexity
This paper employed wavelet coherence and partial wavelet coherence to investigate the time-frequency effect of global economic policy uncertainty on the comovement of five agricultural commodities such as maize, oat, rice, soybean, and wheat using monthly data from January 1997 to December 2019. In general, we observed heterogeneity in comovement structures of the agricultural commodities market at different time-frequency scales which are profound at high frequencies from the bivariate wavelet coherence. The partial wavelet coherence analysis shows that global economic policy uncertainty is a driver of agricultural commodity market connectedness. This implies that extreme changes in economic policy uncertainty have the tendency to influence commodity price comovement. This poses risk to the stability of the agricultural commodities market, which requires the policymaker’s intervention to protect against the spillover risk contagion effect in uncertain times.
Computational Economics
We propose a form of semi-nonparametric regression based on wavelet analysis. Traditional time series methods usually involve either the time or the frequency domain, but wavelets can combine the information from both of these. While wavelet transforms are typically restricted to equally spaced observations an integer power of 2 in number, we show how to go beyond these constraints. We use our methods to construct \patios" for 21 important international commodity price series. These graph the magnitude of the variations in the series at di erent time scales for various subperiods of the full sample.
Theoretical Economics Letters, 2015
This study examines the inter-temporal causal nexus between Indian commodity futures and spot prices by using wavelet analysis. Wavelet analysis offers an effective alternative tool to examine the inter-temporal causal relationship in time as well as frequency domains, providing a deeper understanding of direction, strength and extent of such causal relationship; whereas traditional econometric causality analysis tools focus only on the time domain. The empirical results of wavelet analysis suggest that the Indian commodity futures market has a powerful price discovery function in all the selected commodities, which in turn indicates the efficiency of the Indian commodity futures market.
Energy Economics, 2015
Previous research on the oil market has focused mainly on the static relationship between bivariate oil prices, ignoring the dynamic correlation of bivariate or multivariate oil prices. This study provides a novel perspective on multivariate dynamic correlations for studying the oil market by using an optimal wavelet analysis on the basis of grey correlation. We used China-Daqing and its three reference benchmark oil prices (Brent, Dubai and Minas) as empirical data. Our main findings are as follows. First, the time-frequency phenomena of the analysis results from one-to-one and many-to-one correlation time series support the hypothesis of the regional and global characteristics of the oil market, respectively. Second, the U-shaped wavelet variance plot indicates that the fluctuation intensity of the shortest and longest time-frequency domains plays a leading role in the dynamic process of oil price correlation. For the Chinese government, the oil price adjustment strategy in the short term should reduce the reference weights of Brent, and the long-term strategy should reduce the reference weights of Minas to avoid the risk of a single reference. The investor's portfolio management should pay more attention to the leading oil price of the corresponding period to make clear market timing. Third, the significant lead-lag relationships of oil price correlations
Journal of Futures Markets, 2016
Correlations between oil and agricultural commodities have varied over previous decades, impacted by renewable fuels policy and turbulent economic conditions. We estimate smooth transition conditional correlation models for 12 agricultural commodities and WTI crude oil. While a structural change in correlations occurred concurrently with the introduction of biofuel policy, oil and food price levels are also key influences. High correlation between biofuel feedstocks and oil is more likely to occur when food and oil price levels are high. Correlation with oil returns is strong for biofuel feedstocks, unlike with other agricultural futures, suggesting limited contagion from energy to food markets.
2015
Financialisation of crude oil and its frequent inclusion into investment portfolios raise the demand for analysis of crude oil and stock market indices relationship at various time scales. In this paper, the relationships between crude oil and stock markets in three Islamic stock market indices and three non-Islamic indices are examined by using a time-scale decomposition based on the theory of wavelets. This study employs daily closing price data of Brent crude oil index and the six stock market indices. The oil and stock return series are first decomposed into different time components and then their relationships are investigated over different time scales through wavelet’s estimated correlations. We also characterized the crude oil and stock market relationship for different timescales in an attempt to disentangle the possible existence of comovement during the global financial crisis. The results mainly show evidence of significant time scale effects on the behavior of the oil-...
Energy Economics, 2010
This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright
ECONOMIC COMPUTATION AND ECONOMIC CYBERNETICS STUDIES AND RESEARCH, 2019
This paper investigates how do oil price changes affect the major agricultural commodities (barley, corn, rice, soybean and wheat) in the different timehorizons and in the different market conditions. For computation purposes we employ a wavelet-based quantile approach. We find strong transmission effect from oil only in the tail quantiles in the longer time-horizons, which is especially true for barley, corn and soybean. It is an indication that the agricultural commodities are affected by oil in the periods of increased market turbulence, regardless of whether it is characterized by increasing or decreasing prices of these commodities. Barley and corn experience the spillover effect in the periods of the rising agricultural prices, and this impact reaches almost 30% in the long-term horizon. The wavelet cross-correlation results provide strong evidence that corn and soybean lead oil in midterm and long-term horizons.
SSRN Electronic Journal, 2021
In this paper we exploit the wavelet analysis approach to investigate oil-food price correlation and its determinants in the domains of time and frequency. Wavelet analysis is able to differentiate high frequency from low frequency movements which correspond, respectively, to short and long run dynamics. We show that the significant local correlation between food and oil is only apparent and this is mainly due both to the activity of commodity index investments and, to a lesser extent, to a growing demand from emerging economies. Moreover, the activity of commodity index investments gives evidence of the overall financialisation process. In addition, we employ wavelet entropy to assess the predictability of the time series under consideration at different frequencies. We find that some variables share a similar predictability structure with food and oil. These variables are the ones that move the most along with oil and food. We also introduce a novel measure, the Cross Wavelet Energy Entropy Measure (CWEEM), based on wavelet transformation and information entropy, with the aim of quantifying the intrinsic predictability of food and oil given demand from emerging economies, commodity index investments, financial stress, and global economic activity. The results show that these dynamics are best predicted by global economic activity at all frequencies and by demand from emerging economies and commodity index investments at high frequencies only.
Journal of International Studies
This study examines the validity of the random walk hypothesis for some selected soft agricultural commodity prices within the context of heterogeneous market hypothesis and mean reversion hypothesis. The study employs a battery of traditional unit root tests, GARCH-based models and a novel frequency-based wavelet analysis to analyze daily data sourced from 6th of Jan 1986 to 29 th Dec 2018. Contrary to other existing studies that employed only traditional time domain unit root tests, our results reveal that soft commodity prices are mean reverting, suggesting the existence of potential excess returns for investors. Overall, our results show that the selected soft commodity series are inefficient when we factored in heteroscedascity and frequency domain into our model. Our study is an improvement on the existing studies as we analyze our data using both time and frequency domain estimates. Besides, unlike other studies that did not offer structural breaks, the current study provides structural break dates with major events in the global socioeconomic space, which are key to identifying the date of bubbles and potential signs of commodity price bubbles. Our findings have some critical implications for investors, policy makers,
Journal of International Money and Finance, 2014
This study is the first attempt to investigate both the linear and non-linear Granger causality between wavelet transformed spot and futures oil prices. Our findings consistently indicate bidirectional causality between the spot and futures oil markets at different time scales, under linear and non-linear causality assumptions, and also during the recent financial crisis. Our results tend to shed further light on the ongoing controversy over the relative price discovery role played by spot market as opposed to futures market in oil price fluctuations, especially during periods of high uncertainty.
Risks
Wavelet power spectrum (WPS) and wavelet coherence analyses (WCA) are used to examine the co-movements among oil prices, green bonds, and CO2 emissions on daily data from January 2014 to October 2022. The WPS results show that oil returns exhibit significant volatility at low and medium frequencies, particularly in 2014, 2019–2020, and 2022. Also, the Green Bond Index presents significant volatility at the end of 2019–2020 and the beginning of 2022 at low, medium, and high frequencies. Additionally, CO2 futures’ returns present high volatility at low and medium frequencies, expressly in 2015–2016, 2018, the end of 2019–2020, and 2022. WCA’s empirical findings reveal (i) that oil returns have a negative impact on the Green Bond Index in the medium term. (ii) There is a strong interdependence between oil prices and CO2 futures’ returns, in short, medium, and long terms, as inferred from the time–frequency analysis. (iii) There also is evidence of strong short, medium, and long terms c...
Finance Research Letters, 2017
This paper examines the causal relationship between commodities funds and returns using monthly data for the period May 1997 to August 2015. Given the strong evidence of nonlinearity and structural breaks, we use wavelets to analyse causality between the two variables at both time and frequency domains. Wavelet coherency reveals that these two variables are primarily positively related in the short-run and over the period of 2008 to 2015. When we investigate the phase differences over this period, we observe that flows have predicted returns over the period of 2008 to 2012, with causality running in the other direction thereafter.
Sustainability, 2018
Within the last few decades, the extended use of biodiesel and bioethanol has established interlinkages between energy markets and agricultural commodity markets. The present work examines the bivariate relationships of crude oil-corn and crude oil-soybean futures prices with the assistance of the ARDL cointegration approach. Our findings confirm that crude oil prices affect the prices of agricultural products used in the production of biodiesel, as well as of ethanol, validating the interaction of energy and agricultural commodity markets. The practical value of the present work is that the findings provide policy makers with insight into the interlinkages between agricultural and energy markets to promote biodiesel or bioethanol by affecting crude oil prices. The novelty of the present work stands on the use of futures prices that incorporate all available information and thus are more appropriate to identify supply and demand shocks and price spillovers than real prices. Finally, the period of study includes extremely low, as well as extremely high, crude oil prices and the results illustrate that biofuels cannot be substituted for crude oil and protect economies from energy volatility.
Empirical Economics, 2010
We use (cross) wavelet analysis to decompose the time-frequency effects of oil price changes on the macroeconomy. We argue that the relation between oil prices and industrial production is not clear-cut. There are periods and frequencies where the causality runs from one variable to the other and vice-versa, justifying some instability in the empirical evidence about the macroeconomic effects of oil price shocks. We also show that the volatility of both the inflation rate and the industrial output growth rate started to decrease in the decades of 1950 and 1960.
Within the last few decades, the extended use of biodiesel and bioethanol has established interlinkages between energy markets and agricultural commodity markets. The present work examines the bivariate relationships of crude oil-corn and crude oil-soybean futures prices with the assistance of the ARDL cointegration approach. Our findings confirm that crude oil prices affect the prices of agricultural products used in the production of biodiesel, as well as of ethanol, validating the interaction of energy and agricultural commodity markets. The practical value of the present work is that the findings provide policy makers with insight into the interlinkages between agricultural and energy markets to promote biodiesel or bioethanol by affecting crude oil prices. The novelty of the present work stands on the use of futures prices that incorporate all available information and thus are more appropriate to identify supply and demand shocks and price spillovers than real prices. Finally, the period of study includes extremely low, as well as extremely high, crude oil prices and the results illustrate that biofuels cannot be substituted for crude oil and protect economies from energy volatility.
This paper studies the relationship between oil price and the exchange rates of Organization of Oil Exporting Countries (OPEC) members from February 1999 to March 2016. The wavelet method is applied to combine information from both time and frequency domains, which does not require stationary and decomposition of original time series data. The study found that the strength of the relationship between oil price and exchange rate divides into three main categories, namely oil price leads exchange rate, exchange rate leads oil prices, and the relationship keeps changing. Countries which currencies pegged to US Dollar are lagging against oil price changes, countries with floating exchange rates and countries with an undisclosed weighted basket of international currencies leads the changes in oil price, and countries which their currencies pegged to special drawing right experience changing relationships. This finding suggests that the central banks of OPEC member countries should give importance to shocks on oil prices, while formulating their own exchange rate policy.
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