Sabiia Seb
PortuguêsEspañolEnglish
Embrapa
        Busca avançada

Botão Atualizar


Botão Atualizar

Ordenar por: RelevânciaAutorTítuloAnoImprime registros no formato resumido
Registros recuperados: 18
Primeira ... 1 ... Última
Imagem não selecionada

Imprime registro no formato completo
A Fully Calibrated Generalized CES Programming Model of Agricultural Supply AgEcon
Merel, Pierre R.; Simon, Leo K.; Yi, Fujin.
The use of prior information on supply elasticities to calibrate programming models of agricultural supply has been advocated repeatedly in the recent literature (Heckelei and Britz 2005). Yet, Mérel and Bucaram (2009) have shown that the dual goal of calibrating such models to a reference allocation while replicating an exogenous set of supply elasticities is not always feasible. This article lays out the methodological foundation to exactly calibrate programming models of agricultural supply using generalized CES production functions. We formally derive the necessary and sufficient conditions under which such models can be calibrated to replicate the reference allocation while displaying crop-specific supply responses that are consistent with prior...
Tipo: Conference Paper or Presentation Palavras-chave: Positive mathematical programming; Generalized CES; Supply elasticities; Crop Production/Industries; Production Economics.
Ano: 2010 URL: http://purl.umn.edu/60906
Imagem não selecionada

Imprime registro no formato completo
A multi-period positive mathematical programming approach for assessing economic impact of drought in the Murray-Darling Basin, Australia AgEcon
Qureshi, Muhammad Ejaz; Ahmad, Mobin-ud-Din; Whitten, Stuart M.; Kirby, Mac.
In the last decade, the Murray-Darling Basin (MDB), Australia faced a severe drought which affected its agriculture production. Sustainable diversion limits as proposed in the Australian Government’s basin plan together with climate change is expected to impact on future agriculture production and development in the MDB. We developed a biophysical-economic mathematical model calibrated against the observed multi-period land use data utilising the positive mathematical programming (PMP) approach to evaluate the impacts on agricultural production activities of a range of climate events and policy options. This is an extension of our previous work where the model was calibrated against a single year and focus was on the southern MDB only. The multi-period...
Tipo: Presentation Palavras-chave: Integrated hydrology and economic model; Multi-period calibration; Climate change; Drought; Agriculture; Positive mathematical programming; Resource /Energy Economics and Policy.
Ano: 2012 URL: http://purl.umn.edu/124418
Imagem não selecionada

Imprime registro no formato completo
A PROGRAMAÇÃO MATEMÁTICA POSITIVA COMO INSTRUMENTO DE CALIBRAÇÃO E PRESCRIÇÃO DOS MODELOS DE OFERTA AGRÍCOLA AgEcon
Fragoso, Rui Manuel de Sousa; Carvalho, Maria Leonor da Silva; Henriques, Pedro Damiao de Sousa.
Neste artigo avalia-se a capacidade de calibração e de prescrição de resultados de um modelo de oferta agrícola da Região Alentejo. A capacidade de calibração é analisada para o regime de preços e de ajudas agrícolas em vigor no ano 2000, comparando os resultados de diferentes formas de especificação da função dos custos variáveis totais do modelo de programação matemática positiva com os resultados do modelo tradicional de programação linear e com os dados estatísticos observados. Depois de calibrado, o modelo de programação matemática positiva foi utilizado na prescrição dos resultados relativos ao cenário de preços e ajudas em vigor no ano de 2004. Concluiu-se que a programação matemática positiva para além de ser um eficaz instrumento de calibração dos...
Tipo: Conference Paper or Presentation Palavras-chave: Programação matemática positiva; Oferta agrícola; Calibração; Prescrição; Positive mathematical programming; Agricultural supply; Calibration; Prescription; Agribusiness.
Ano: 2008 URL: http://purl.umn.edu/108610
Imagem não selecionada

Imprime registro no formato completo
A Sectoral Model for Analyzing Alternative Technologies in Pig Farming AgEcon
Helming, John F.M.; Surry, Yves R..
This paper develops a demand-augmented positive mathematical programming model to analyze the relationship between environmental pollution from animal manure, manure policies and different pork production systems in the Netherlands. The model features substitution of conventional and alternative pork from the demand side and endogenous manure prices. It is found that policies that put restrictions on environmental pollution from manure decreases the conventional pork production systems, but increases organic pork production systems. The latter is considered an improved system from both an animal welfare and environmental point of view.
Tipo: Conference Paper or Presentation Palavras-chave: Societal concerns; Positive mathematical programming; Pork; Markets; Policies; Livestock Production/Industries.
Ano: 2005 URL: http://purl.umn.edu/24774
Imagem não selecionada

Imprime registro no formato completo
Assessing the Opportunity Cost of Growing a Bioenergy Crop in California: a PMP Approach AgEcon
Yi, Fujin; Merel, Pierre R.; Lee, Juhwan; Six, Johan.
A significant increase in demand for fuel ethanol in California should be expected if all gasoline sold in the state were to be blended with 10% ethanol, as envisaged in the State Alternative Fuels Plan. This paper assesses the potential of California agriculture to supply biofuel feedstock in the form of switchgrass. We construct a fully calibrated, multi-region, multi-input and multi-output model of agricultural supply for California’s Central Valley based on the principles of Positive Mathematical Programming. We exploit the biogeochemical model DAYCENT to estimate production functions for switchgrass in each agricultural region. We then predict the extent and location of potential switchgrass production in the Central Valley. Our results suggest that...
Tipo: Conference Paper or Presentation Palavras-chave: California agriculture; Bioenergy crop; Opportunity cost; Positive mathematical programming; Crop Production/Industries; Research Methods/ Statistical Methods; Resource /Energy Economics and Policy.
Ano: 2011 URL: http://purl.umn.edu/104519
Imagem não selecionada

Imprime registro no formato completo
Calibration of an Agricultural Sector Model for the Region Khorezm (Uzbekistan) based on Survey Data AgEcon
Mueller, Marc; Djanibekov, Nodir.
The paper describes the approach used for the calibration of a price-endogenous programming model, developed for the agricultural sector of the region Khorezm in Uzbekistan. Extensive datasets from farm surveys were used to parameterize the model, which nevertheless tended to over-specialization and failed in general to replicate the observed levels of primal model variables. Calibration of the model with “Positive Mathematical Programming” approaches was not satisfying as the additional cost terms introduced to replicate the observed situation were in many cases not plausible and deviated substantially from any available information on cost structure of the agricultural production activities in the study region. After revising the survey data it became...
Tipo: Conference Paper or Presentation Palavras-chave: Supply model calibration; Positive mathematical programming; Technology coefficient estimation; Agricultural and Food Policy; Research Methods/ Statistical Methods; C6; C8; Q1.
Ano: 2009 URL: http://purl.umn.edu/50354
Imagem não selecionada

Imprime registro no formato completo
Cost-Effectiveness Evaluation of Swiss Agri-Environmental Measures on Sector Level AgEcon
Schader, Christian; Sanders, Jurn; Offermann, Frank; Lampkin, Nicolas; Stolze, Matthias.
This paper focuses on non-linear programming models and their suitability for ex-ante evaluations of agri-environmental policies on sector level. An approach is presented to compare organic farming payments as a multi-objective policy, with other, more targeted agri-environmental policies in Switzerland. The Swiss version of the comparative static sector-consistent farm group model FARMIS is able to group the sector’s farms into organic and non-organic farms and optimise them separately. CH-FARMIS is expanded with three modules particularly for this study: a) allowing for the simulation of uptake; b) integrating life cycle assessment data for energy use, eutrophication and biodiversity; and c) estimating the policy and farm-group-specific public...
Tipo: Conference Paper or Presentation Palavras-chave: Positive mathematical programming; Life cycle assessment; Organic farming; Environmental indicators; Economic efficiency; Agricultural and Food Policy; Farm Management; Research Methods/ Statistical Methods.
Ano: 2008 URL: http://purl.umn.edu/6604
Imagem não selecionada

Imprime registro no formato completo
Evaluating Changes in Cropping Patterns due to the 2003 CAP Reform. An Ex-post Analysis of Different PMP Approaches Considering New Activities AgEcon
Blanco, Maria; Cortignani, Raffaele; Severini, Simone.
Replaced with revised version of paper 02/22/08.
Tipo: Conference Paper or Presentation Palavras-chave: Ex-post policy evaluation; Positive mathematical programming; CAP reform; Agricultural and Food Policy; Crop Production/Industries; Research Methods/ Statistical Methods.
Ano: 2008 URL: http://purl.umn.edu/6674
Imagem não selecionada

Imprime registro no formato completo
Farm production costs estimation trough PMP Models: an application in three Italian Regions AgEcon
Arfini, Filippo; Donati, Michele; Marongiu, Sonia; Cesaro, Luca.
The objective of this paper is to present a Generalised Positive Mathematical Programming model suitable for the estimation of variable cost of production associated with different farm activities. This work present, discuss and demonstrates that the Generalised PMP model is a useful theoretical framework for the representation of farm choice, including for the description of costs related to the production function chosen by each entrepreneur. For this characteristics the model can be used for the farms belonging the FADN sample providing a powerful tools for researcher that would like to know variable costs of production for agricultural activities or estimate the impact of agricultural policy and market reform at regional and sectorial level. The main...
Tipo: Presentation Palavras-chave: Variable cost of production; Positive mathematical programming; Farm accountancy data network; Production Economics; Q12; C61; Q18; C38.
Ano: 2012 URL: http://purl.umn.edu/124117
Imagem não selecionada

Imprime registro no formato completo
Innovation in Estimation of Revenue and Cost Functions in PMP Using FADN Information at Regional Level AgEcon
Arfini, Filippo; Donati, Michele; Paris, Quirino.
The objective of this paper is to present an evolution of PMP model suitable to estimate the revenue function and to provide price elasticity due to the variation of subsidies at farm level, especially if they are decoupled. This problem arises when individual data of farm households in a given region, coming from FADN, are used for implement PMP models finalized to policy analysis. This paper presents the theoretical background of the proposed innovations and empirical evidence on the basis of a sample of farms included in FADN database in Italy.
Tipo: Conference Paper or Presentation Palavras-chave: Positive mathematical programming; Demand function; Agricultural policies evaluation; Agricultural and Food Policy; Demand and Price Analysis.
Ano: 2008 URL: http://purl.umn.edu/44008
Imagem não selecionada

Imprime registro no formato completo
Introducing deficit irrigation crop techniques derived by crop growth models into a Positive Mathematical Programming model AgEcon
Severini, Simone; Cortignani, Raffaele.
There is a growing policy pressure to reduce water use in agriculture when this generates sufficiently large environmental benefits and increases the well-being of other water users. Several analysis investigate farmers’ response to water policy by means of mathematical programming models including Positive Mathematical Programming (PMP). The originals PMP methods refer only to activities observed in the reference period. However, under the pressure of new water policies, farmers can adjust not only their cropping patterns but also the irrigation techniques they use. In particular, they could introduce water deficit irrigation crop techniques that were not profitable in past conditions. This paper proposes an extension of the Röhm and Dabbert approach...
Tipo: Conference Paper or Presentation Palavras-chave: Positive mathematical programming; Water policies; Deficit irrigation; Crop Production/Industries.
Ano: 2008 URL: http://purl.umn.edu/44010
Imagem não selecionada

Imprime registro no formato completo
Irrigation water pricing between governmental policies and farmers’ perception: Implications for green-houses horticultural production in Teboulba (Tunisia) AgEcon
Chebil, Ali; Frija, Aymen; Thabet, Chokri.
A positive mathematical programming model was constructed in this study to assess the effect of three water pricing scenarios on Teboulba’s agricultural production systems. The effects of these scenarios were estimated for three groups of farmers from three irrigated districts. Results show that water demand in group 1 remains inelastic until achieving the price of 0.20 TD. A price above this level decreases water consumption, farmer’s incomes as well as seasonal labor demand. For groups 2 and 3, the water demand curves remain highly inelastic even with a full cost recovery price. However, once reaching this last price, the model shows important income reductions reaching 20% of the current observed income. Moreover, a pricing policy aiming to recover...
Tipo: Article Palavras-chave: Water pricing; Positive mathematical programming; Greenhouses; Economic impact; Teboulba; Environmental Economics and Policy; Farm Management; Resource /Energy Economics and Policy; Q15; Q18.
Ano: 2010 URL: http://purl.umn.edu/118863
Imagem não selecionada

Imprime registro no formato completo
KRAM - A Sector Model of Danish Agriculture - Background and Framework Development AgEcon
Wiborg, Torben.
A model of the Danish agricultural sector named KRAM (KVL's Regionalized Agricultural Model) is developed in this paper. KRAM can be described as a spatial, dynamic, nonlinear, programming sector model. KRAM's purpose is to make policy analysis in the complex market conditions Danish agriculture is working under today. In order to do this in the best possible way the model optimizes the production functions on a very disaggregated level. This allows for analysis of changes in physical constraints to production, as well as price changes. The model is capable of calculating some environmental effects of agricultural production, and provides detailed spatial description of the agricultural economy and production. The time horizon is 10 years, and the model...
Tipo: Working or Discussion Paper Palavras-chave: Agricultural production; Positive mathematical programming; Dynamic agricultural sector model; Regions; Markov chain; Structural development; Crops; Pigs; Cows; GAMS; Production Economics.
Ano: 1998 URL: http://purl.umn.edu/18322
Imagem não selecionada

Imprime registro no formato completo
PMP and Uniqueness of the Calibrating Solution - Revision AgEcon
Paris, Quirino.
This paper demonstrates the existence of a unique solution of the PMP problem when both observed output quantities and limiting input prices are taken as calibrating benchmarks. This version of PMP avoids the use of a user-determined small positive number ε originally introduced for guaranteeing that the dual (shadow) price of binding input constraints be positive. Furthermore, the paper shows how to obtain endogenous output supply and input demand elasticities that match available information about them in the form of previously estimated parameters for an entire region or sector. The framework is applied to a sample of farms also for the case that admits no production for some of the crop activities. The calibrating solution is very close to the observed...
Tipo: Working Paper Palavras-chave: Positive mathematical programming; Solution uniqueness; Supply elasticities; Calibrating model; Productivity Analysis; Research Methods/ Statistical Methods; C6.
Ano: 2015 URL: http://purl.umn.edu/200491
Imagem não selecionada

Imprime registro no formato completo
Positive Mathematical Programming: a Comparison of Different Specification Rules AgEcon
Fragoso, Rui Manuel de Sousa; Carvalho, Maria Leonor da Silva; Henriques, Pedro Damiao de Sousa.
In this paper, the prescriptive capacity of different types of positive mathematical programming models applied to the Alentejo agricultural sector is analysed. Model results are compared for 2000 and 2004 agricultural price and subsidies scenarios, regarding optimal combination of activities. Thus, it is tested, on one hand, models capacity to reproduce Alentejo agricultural sector behaviour, and by the other hand, their response and adjustment capacities to changes in prices and in agricultural policy.
Tipo: Conference Paper or Presentation Palavras-chave: Positive mathematical programming; Agricultural supply; Alentejo; Research Methods/ Statistical Methods.
Ano: 2008 URL: http://purl.umn.edu/44242
Imagem não selecionada

Imprime registro no formato completo
Revenue and Cost Functions in PMP: a Methodological Integration for a Territorial Analysis of CAP AgEcon
Arfini, Filippo; Donati, Michele; Grossi, L.; Paris, Quirino.
An integrated policy evaluation tool is proposed for assessing the effects of agricultural policy measures using all the information available at farm level. The tool combines the positive mathematical programming methodology with the cluster analysis technique by using the same panel of data. The PMP model proposed here allows to measure the effects of policy in term of agricultural supply responses including output market price variations. The novel procedure by which the PMP model is articulated permits to recover the set of farm level demand functions for agricultural products and the cost function characterizing the given sample of farms. Cluster analysis is useful for better appreciating the behaviour of farms before and after the policy scenario...
Tipo: Conference Paper or Presentation Palavras-chave: Positive mathematical programming; Cluster analysis; Integrated tool; Agricultural policies; Policy evaluation; Agricultural and Food Policy; Research Methods/ Statistical Methods.
Ano: 2008 URL: http://purl.umn.edu/6636
Imagem não selecionada

Imprime registro no formato completo
Single payment scheme and dual values of land in PMP models AgEcon
Judez, Lucinio; de Andres, Rosario; Urzainqui, Elvira.
Land dual values are one of the important aspects of the results of mathematical programming models used to evaluate the impact of agricultural policy measures at regional and farm level. When the decoupling of direct payments and the payment entitlements per hectare are included in PMP models in the context of the Single Payment Scheme (SPS), the analysis of the land dual values is more complex than in models which do not take these aspects into account. In this paper, we present a theoretical analysis of the land dual values when the SPS is included in PMP farm models. This theoretical analysis is carried out for the base year (linear model) and for a simulated year (quadratic model).The results of this analysis are illustrated by comparing numerically...
Tipo: Conference Paper or Presentation Palavras-chave: Positive mathematical programming; Single Payment Scheme or Single Farm Payment; Land dual values; Agricultural and Food Policy; C61; Q18.
Ano: 2011 URL: http://purl.umn.edu/98997
Imagem não selecionada

Imprime registro no formato completo
The Effect of Climate Change on Land Use and Wetlands Conservation in Western Canada: An Application of Positive Mathematical Programming AgEcon
Withey, Patrick; van Kooten, G. Cornelis.
This study examines the impact of climate change on land use in the Prairie Pothole Region of Western Canada, with particular emphasis on how climate change will impact wetlands. A multi-region Positive Mathematical Programming model calibrates land use in the area to observed acreage in 2006. Policy simulations for both climate effects as well as the effects of biofuel policies determine how climate change will affect land use and wetlands. Given that the model calibrates to observed acreage, the policies provide a realistic view of how land use might change from current levels, given the effects of climate change. Results indicate that climate change could decrease wetlands in this area by as much as 50 percent. The effect will be very different...
Tipo: Working or Discussion Paper Palavras-chave: Positive mathematical programming; Wetlands conservation; Land use change; Climate change; Biofuels; Prairie pothole region; Environmental Economics and Policy; C02; C63; Q15; Q54; Q57; Q24; Q25.
Ano: 2011 URL: http://purl.umn.edu/107095
Registros recuperados: 18
Primeira ... 1 ... Última
 

Empresa Brasileira de Pesquisa Agropecuária - Embrapa
Todos os direitos reservados, conforme Lei n° 9.610
Política de Privacidade
Área restrita

Embrapa
Parque Estação Biológica - PqEB s/n°
Brasília, DF - Brasil - CEP 70770-901
Fone: (61) 3448-4433 - Fax: (61) 3448-4890 / 3448-4891 SAC: https://www.embrapa.br/fale-conosco

Valid HTML 4.01 Transitional