scholarly journals Commodity Prices Revisited

2000 ◽  
Vol 29 (2) ◽  
pp. 125-137 ◽  
Author(s):  
William G. Tomek
Keyword(s):  
Conceptual Models ◽  
Structural Parameters ◽  
Commodity Prices ◽  
Decision Makers ◽  
Model Specification ◽  
Price Expectations ◽  
Empirical Results ◽  
Price Series ◽  
Typical Time ◽  
Random Variability

Empirical models of commodity prices are potentially important aids to decision-makers, especially as the economy has grown more complex. A typical time series of commodity prices exhibits positive autocorrelation, occasional spikes, and random variability, and conceptual models have been developed to explain this behavior. But, the leap from theory to empirical applications is large because of model specification and data quality problems. When modeling price expectations, for example, should a price series be deflated and if so, by what deflator? The choice can have a large effect on empirical results. Nonetheless, it is possible in some applications to obtain relatively stable estimates of structural parameters that are useful for addressing specific problems. This may not happen often, however, because the incentives in academia do not encourage rigorous, in-depth appraisals of empirical results.

scholarly journals Commodity Food Prices: Review and Empirics

2013 ◽  
Vol 2013 ◽  
pp. 1-15 ◽  
Author(s):  
Anthony N. Rezitis ◽  
Maria Sassi
Keyword(s):  
Literature Review ◽  
Structural Breaks ◽  
Price Index ◽  
Commodity Prices ◽  
Food Prices ◽  
Food Price ◽  
Agricultural Commodity ◽  
Structural Trend ◽  
Empirical Results ◽  
Price Series

The present paper provides a literature review of studies examining the potential causes and consequences of recent surges in food and agricultural commodity prices. Furthermore, this paper uses the structural trend methodology proposed by Koopman et al. (2009) to analyze movements in the IMF monthly commodity food price index for the period 1992(11)–2012(10) and to provide forecasts for the period 2012(11)–2014(12). The empirical results indicate that commodity food prices present seasonality and cyclicality with the longest periodicity of two years. The empirical findings identify certain structural breaks in commodity food price series as well as outliers. These structural breaks seem to capture the trend component of the price series well, while the outliers take account of temporal effects, that is, short-lived spikes. Finally, the presented forecasts show high and volatile commodity food prices.

scholarly journals Probability elicitation using geostatistics in hydrocarbon exploration

2021 ◽  
Author(s):  
André Luís Morosov ◽  
Reidar Brumer Bratvold
Keyword(s):  
Value Creation ◽  
Decision Process ◽  
Conceptual Models ◽  
Joint Probability ◽  
Decision Makers ◽  
Hydrocarbon Exploration ◽  
Joint Probability Distribution ◽  
Proof Of Concept ◽  
Geological Information ◽  
Decision Supporting

AbstractThe exploratory phase of a hydrocarbon field is a period when decision-supporting information is scarce while the drilling stakes are high. Each new prospect drilled brings more knowledge about the area and might reveal reserves, hence choosing such prospect is essential for value creation. Drilling decisions must be made under uncertainty as the available geological information is limited and probability elicitation from geoscience experts is key in this process. This work proposes a novel use of geostatistics to help experts elicit geological probabilities more objectively, especially useful during the exploratory phase. The approach is simpler, more consistent with geologic knowledge, more comfortable for geoscientists to use and, more comprehensive for decision-makers to follow when compared to traditional methods. It is also flexible by working with any amount and type of information available. The workflow takes as input conceptual models describing the geology and uses geostatistics to generate spatial variability of geological properties in the vicinity of potential drilling prospects. The output is stochastic realizations which are processed into a joint probability distribution (JPD) containing all conditional probabilities of the process. Input models are interactively changed until the JPD satisfactory represents the expert’s beliefs. A 2D, yet realistic, implementation of the workflow is used as a proof of concept, demonstrating that even simple modeling might suffice for decision-making support. Derivative versions of the JPD are created and their effect on the decision process of selecting the drilling sequence is assessed. The findings from the method application suggest ways to define the input parameters by observing how they affect the JPD and the decision process.

scholarly journals A Reappraisal of the Prebisch-Singer Hypothesis Using Wavelets Analysis

2021 ◽  
Vol 14 (7) ◽  
pp. 319
Author(s):  
Hany Fahmy
Keyword(s):  
International Trade ◽  
Structural Breaks ◽  
Developing Economies ◽  
Commodity Prices ◽  
Commodity Price ◽  
Data Set ◽  
Price Series ◽  
Long Run ◽  
Starting Point ◽  
The Impact

The Prebisch-Singer (PS) hypothesis, which postulates the presence of a downward secular trend in the price of primary commodities relative to manufacturers, remains at the core of a continuing debate among international trade economists. The reason is that the results of testing the PS hypothesis depend on the starting point of the technical analysis, i.e., stationarity, nonlinearity, and the existence of structural breaks. The objective of this paper is to appraise the PS hypothesis in the short- and long-run by employing a novel multiresolution wavelets decomposition to a unique data set of commodity prices. The paper also seeks to assess the impact of the terms of trade (also known as Incoterms) on the test results. The analysis reveals that the PS hypothesis is not supported in the long run for the aggregate commodity price index and for most of the individual commodity price series forming it. Furthermore, in addition to the starting point of the analysis, the results show that the PS test depends on the term of trade classification of commodity prices. These findings are of particular significance to international trade regulators and policymakers of developing economies that depend mainly on primary commodities in their exports.

scholarly journals Interbasin water transfer in a changing world: A new conceptual model

2021 ◽  
pp. 030913332110650
Author(s):  
Edward Rollason ◽  
Pammi Sinha ◽  
Louise J Bracken
Keyword(s):  
Water Scarcity ◽  
Conceptual Models ◽  
Management Strategies ◽  
Temporal Distribution ◽  
Water Transfer ◽  
Decision Makers ◽  
Global Issue ◽  
Proposed Model ◽  
Interbasin Water Transfer ◽  
Water Scarce

Water scarcity is a global issue, affecting in excess of four billion people. Interbasin Water Transfer (IBWT) is an established method for increasing water supply by transferring excess water from one catchment to another, water-scarce catchment. The implementation of IBWT peaked in the 1980s and was accompanied by a robust academic debate of its impacts. A recent resurgence in the popularity of IBWT, and particularly the promotion of mega-scale schemes, warrants revisiting this technology. This paper provides an updated review, building on previously published work, but also incorporates learning from schemes developed since the 1980s. We examine the spatial and temporal distribution of schemes and their drivers, review the arguments for and against the implementation of IBWT schemes and examine conceptual models for assessing IBWT schemes. Our analysis suggests that IBWT is growing in popularity as a supply-side solution for water scarcity and is likely to represent a key tool for water managers into the future. However, we argue that IBWT cannot continue to be delivered through current approaches, which prioritise water-centric policies and practices at the expense of social and environmental concerns. We critically examine the Socio-Ecological Systems and Water-Energy-Food (WEF) Nexus models as new conceptual models for conceptualising and assessing IBWT. We conclude that neither model offers a comprehensive solution. Instead, we propose an enhanced WEF model (eWEF) to facilitate a more holistic assessment of how these mega-scale engineering interventions are integrated into water management strategies. The proposed model will help water managers, decision-makers, IBWT funders and communities create more sustainable IBWT schemes.

Citizens' Voice and Adoption of Pakistani E-Government Services

2015 ◽  
pp. 246-262 ◽  
Author(s):  
Muhammad Ovais Ahmad ◽  
Jouni Markkula ◽  
Markku Oivo
Keyword(s):  
Developing Countries ◽  
Data Privacy ◽  
Decision Makers ◽  
Service Adoption ◽  
Government Services ◽  
Empirical Results ◽  
Factors Influencing ◽  
Use Of Technology ◽  
Potential Problems ◽  
The Voice

Even though there is emerging literature on e-government, research focused on potential problems related to citizens' adoption of e-government services in developing countries is still limited. As a developing country, e-government services in Pakistan have witnessed prolific advancements over the years. Since 2002, Pakistan has strategically adopted e-government as a part of its policy. In this chapter, the factors influencing citizens' e-government service adoption in Pakistan are examined using the unified theory of acceptance and use of technology model. The findings indicate that, in addition to the lack of awareness and data privacy, all of the factors specified by the model have an effect on the adoption of these services in Pakistan. The empirical results highlight the voice of citizens concerning the usage of the services. This information can be used by the policy and decision makers to promote services that correspond better to the needs of the citizens.

Citizens' Voice and Adoption of Pakistani E-Government Services

2015 ◽  
pp. 1155-1171
Author(s):  
Muhammad Ovais Ahmad ◽  
Jouni Markkula ◽  
Markku Oivo
Keyword(s):  
Developing Countries ◽  
Data Privacy ◽  
Decision Makers ◽  
Service Adoption ◽  
Government Services ◽  
Empirical Results ◽  
Factors Influencing ◽  
Use Of Technology ◽  
Potential Problems ◽  
The Voice

Even though there is emerging literature on e-government, research focused on potential problems related to citizens' adoption of e-government services in developing countries is still limited. As a developing country, e-government services in Pakistan have witnessed prolific advancements over the years. Since 2002, Pakistan has strategically adopted e-government as a part of its policy. In this chapter, the factors influencing citizens' e-government service adoption in Pakistan are examined using the unified theory of acceptance and use of technology model. The findings indicate that, in addition to the lack of awareness and data privacy, all of the factors specified by the model have an effect on the adoption of these services in Pakistan. The empirical results highlight the voice of citizens concerning the usage of the services. This information can be used by the policy and decision makers to promote services that correspond better to the needs of the citizens.

scholarly journals The network boundary specification problem in the global and world city research: investigation of the reliability of empirical results from sampled networks

2020 ◽  
Author(s):  
Vladimír Pažitka ◽  
Dariusz Wójcik
Keyword(s):  
Network Analysis ◽  
Structural Parameters ◽  
Empirical Studies ◽  
World City ◽  
Urban Networks ◽  
Empirical Results ◽  
Network Boundary ◽  
City Network ◽  
Network Centralities ◽  
Modelling Approaches

AbstractDespite the well-known dependence of vertex and network structural parameters on network boundary specification employed by researchers, there has so far been effectively no discussion of this methodological caveat in the global and world city literature. Given the reliance of empirical studies of urban networks on the sampling of underlying actors that form these networks by their interactions, we consider it of key importance to examine the dependence of network centralities of cities on network boundary specification. We consider three distinctive modelling approaches based on: (a) office networks, (b) ownership ties and (c) inter-organisational projects. Our results indicate that city network centralities obtained from sampled networks are highly consistent with those obtained from whole network analysis for samples featuring as little as 4% (office networks), 10% (ownership ties) and 25% (inter-organisational projects) of the underlying actors.

scholarly journals Breaks, trends and unit roots in commodity prices: a robust investigation

2014 ◽  
Vol 18 (1) ◽  
Author(s):  
Atanu Ghoshray ◽  
Mohitosh Kejriwal ◽  
Mark Wohar
Keyword(s):  
Unit Root ◽  
Structural Breaks ◽  
Commodity Prices ◽  
Unit Roots ◽  
Commodity Price ◽  
Policy Implications ◽  
Price Shocks ◽  
Price Series ◽  
Commodity Price Shocks ◽  
Trend Breaks

AbstractThis paper empirically examines the time series behavior of primary commodity prices relative to manufactures with reference to the nature of their underlying trends and the persistence of shocks driving the price processes. The direction and magnitude of the trends are assessed employing a set of econometric techniques that is robust to the nature of persistence in the commodity price shocks, thereby obviating the need for unit root pretesting. Specifically, the methods allow consistent estimation of the number and location of structural breaks in the trend function as well as facilitate the distinction between trend breaks and pure level shifts. Further, a new set of powerful unit root tests is applied to determine whether the underlying commodity price series can be characterized as difference or trend stationary processes. These tests treat breaks under the unit root null and the trend stationary alternative in a symmetric fashion thereby alleviating the procedures from spurious rejection problems and low power issues that plague most existing procedures. Relative to the extant literature, we find more evidence in favor of trend stationarity suggesting that real commodity price shocks are primarily of a transitory nature. We conclude with a discussion of the policy implications of our results.

scholarly journals The Economics of Outdoor Recreation Congestion: A Case study of Camping

1979 ◽  
Vol 8 (1) ◽  
pp. 13-16 ◽  
Author(s):  
P. Geoffrey Allen ◽  
Thomas H. Stevens
Keyword(s):  
Outdoor Recreation ◽  
Model Misspecification ◽  
Economic Value ◽  
High Density ◽  
Model Specification ◽  
Demand Model ◽  
Empirical Results ◽  
Congestion Effects

Bias in estimating recreational values may result if congestion is ignored in the demand model specification. Theoretical and empirical considerations pertaining to recreation congestion are summarized. Empirical results for camping in Western Massachusetts are presented which demonstrate the potential degree of bias from demand model misspecification. The results indicate that recreational values may be strongly influenced by congestion effects and that camping areas with relatively low densities may have a higher economic value than high density areas with similar facilities.

The Direction of Wage Spillovers in Manufacturing

ILR Review ◽  
1982 ◽  
Vol 36 (1) ◽  
pp. 102-112 ◽  
Author(s):  
Susan Vroman
Keyword(s):  
Union Wage ◽  
Manufacturing Sector ◽  
Spillover Effect ◽  
Traditional View ◽  
Model Specification ◽  
Wage Change ◽  
Empirical Results ◽  
Nonunion Wage ◽  
Data Period ◽  
The U.S

This study develops a model of wage behavior for both union and nonunion workers in the U.S. manufacturing sector and tests that model with separate union and nonunion wage-change series covering the period 1960 to 1978. The empirical results support the traditional view that union wage behavior influences or spills over into nonunion wage changes but not vice versa. These results are of particular interest because they contrast sharply with an earlier study by Flanagan that reported an opposite spillover effect. Flanagan's results are shown to be quite sensitive to the choice of model specification and data period.

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