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Construcción de unidades representativas de producción porcina y análisis de su viabilidad económica en el período 2009-2018 Agrociencia
Zavala-Pineda,M. Jesica; Salas-González,J. María; Leos-Rodríguez,J. Antonio; Sagarnaga-Villegas,L. Myriam.
En este estudio se destaca la relevancia de los estudios prospectivos en el diseño de una política agropecuaria diferenciada para México y en la identificación de los efectos potenciales de políticas sectoriales diferenciadas. Por tanto, el objetivo del estudio fue analizar la viabilidad económica de unidades representativas de producción (URP) porcícola en los estados de Jalisco, Sonora y Guanajuato. La técnica de paneles se usó para modelar 15 URP con la participación de 137 productores, con granjas similares en tecnología, escala, sistema de producción, ubicación geográfica y mercado de destino del producto. Mediante consensos se identificó la información técnica y financiera relevante para construir el Año Base 2008. Con esta información y empleando el...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Análisis prospectivo; Monte Carlo; Paneles; Simulación; Transferencias gubernamentales.
Ano: 2012 URL: http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1405-31952012000700008
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ANÁLISE QUANTITATIVA DO RISCO TÉCNICO-ECONÔMICO DE UM TRATOR FLORESTAL SKIDDER BIOFIX
Miyajima, Ricardo Hideaki; Tonin, Rodrigo Petrongari; Fenner, Paulo Torres; Simões, Danilo.
Os custos da colheita florestal, de forma abrangente, podem ser definidos como a quantificação econômica dos fatores produtivos, determinados em sua maioria pelo modal utilizado. Todavia, um elemento presente no conhecimento dos custos desses modais é a incerteza nas estimativas, devido ao conjunto de fatores envolvidos ou da insuficiência de informações. À vista disso, objetivou-se neste estudo construir um modelo estocástico, a partir da produtividade operacional de um trator florestal skidder empregado na extração de Eucalyptus sp., para quantificar os riscos técnico-econômicos por meio da simulação de Monte Carlo. A análise técnico-econômica teve como premissa o estudo de tempos e métodos, seguida da estimativa do custo horário do trator florestal...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Colheita florestal; Custos de extração; Monte Carlo; Silvicultura; Tempos e métodos.
Ano: 2017 URL: http://revistas.ufpr.br/biofix/article/view/56339
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Selecting “the best” nonstationary Generalized Extreme Value (GEV) distribution: on the influence of different numbers of GEV-models Bragantia
Xavier,Ana Carolina Freitas; Blain,Gabriel Constantino; Morais,Marcos Vinicius Bueno de; Sobierajski,Graciela da Rocha.
ABSTRACT The selection of an appropriate nonstationary Generalized Extreme Value (GEV) distribution is frequently based on methods, such as Akaike information criterion (AIC), second-order Akaike information criterion (AICc), Bayesian information criterion (BIC) and likelihood ratio test (LRT). Since these methods compare all GEV-models considered within a selection process, the hypothesis that the number of candidate GEV-models considered in such process affects its own outcomehas been proposed. Thus, this study evaluated the performance of these four selection criteria as function of sample sizes, GEV-shape parameters and different numbers candidate GEV-models. Synthetic series generated from Monte Carlo experiments and annual maximum daily rainfall...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Monte Carlo; GEV; MIROC5; Downscaling.
Ano: 2019 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052019000400606
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Uncertainty of the density of moist air: Gum x Monte Carlo BABT
Canaves Junior,Moacyr; Pompéia,Pedro José.
In this study two methods of evaluation of uncertainty, the law of propagation of uncertainties (as recommended by GUM) and the method of Monte Carlo, are compared. As a particular case the determination of the density of moist air was considered The results show that there are some differences between both methods.
Tipo: Info:eu-repo/semantics/article Palavras-chave: Density of moist air; Propagation of uncertainties; Monte Carlo.
Ano: 2006 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132006000200014
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Robustness of asymptotic and bootstrap tests for multivariate homogeneity of covariance matrices Ciência e Agrotecnologia
Silva,Roberta Bessa Veloso; Ferreira,Daniel Furtado; Nogueira,Denismar Alves.
The present work emphasizes the importance of testing hypothesis on homogeneity of covariance matrices from multivariate k populations. The violation of the assumption of the homogeneity of covariance matrices affects the performance of the tests and the coverage probability of the confidence regions. This work intends to apply two tests of homogeneity of covariance and to evaluate type I error rates and power using Monte Carlo simulation in normal populations and robustness in non normal populations. Multivariate Bartlett's test (MBT) and its bootstrap version (MBTB) were used. Different configurations are tested combining sample sizes, number of variates, correlation and number of populations. Results show that the bootstrap test was considered superior...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Simulation type I error rate power; Monte Carlo.
Ano: 2008 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542008000100023
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Alternativas para o teste t com variâncias heterogêneas avaliadas por meio de simulação Ciência e Agrotecnologia
Silva,Roberta Bessa Veloso; Ferreira,Daniel Furtado.
Conduziu-se este trabalho com o objetivo de avaliar os riscos de se tomar decisões erradas (erro tipo I e erro tipo II), com o aumento da diferença entre as variâncias populacionais, por meio de simulação computacional, utilizando-se o teste t de Student com o número de graus de liberdade sendo aproximado pelas alternativas de Satterthwaite (1946), valor mínimo υ = min (n1 - 1, n2 - 1) e pelo método de bootstrap. Duas populações foram geradas, e a variância da população 1 foi igual a um (σ21), e a da população 2 foi especificada em função da razão σ22/σ21, a qual assume os valores 1, 2, 8 e 16. Usando essas abordagens diferentes para o teste t, avaliaram-se as taxas de erro tipo I e tipo II. Todos os critérios controlaram adequadamente a taxa de erro tipo...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Erros tipo I e tipo II; Monte Carlo; Bootstrap.
Ano: 2003 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542003000100023
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Sisvar: a Guide for its Bootstrap procedures in multiple comparisons Ciência e Agrotecnologia
Ferreira,Daniel Furtado.
Sisvar is a statistical analysis system with a large usage by the scientific community to produce statistical analyses and to produce scientific results and conclusions. The large use of the statistical procedures of Sisvar by the scientific community is due to it being accurate, precise, simple and robust. With many options of analysis, Sisvar has a not so largely used analysis that is the multiple comparison procedures using bootstrap approaches. This paper aims to review this subject and to show some advantages of using Sisvar to perform such analysis to compare treatments means. Tests like Dunnett, Tukey, Student-Newman-Keuls and Scott-Knott are performed alternatively by bootstrap methods and show greater power and better controls of experimentwise...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Monte Carlo; Type I error; Power.
Ano: 2014 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542014000200001
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Comparações múltiplas bayesianas em modelos normais homocedásticos e heterocedásticos Ciência e Agrotecnologia
Andrade,Paulo César de Resende; Ferreira,Daniel Furtado.
Procedimentos de comparações múltiplas são utilizados para comparar médias de níveis de um fator, porém, os testes mais populares apresentam problemas de ambiguidade dos resultados e de controle do erro tipo I, além de terem seus desempenhos influenciados negativamente no caso de heterogeneidade de variâncias e não balanceamento. Objetivou-se, neste trabalho propor alternativas bayesianas para comparações múltiplas considerando os casos de homogeneidade e heterogeneidade de variâncias. A metodologia utilizada nesse trabalho foi baseada na distribuição a posteriori t multivariada. Foram geradas k cadeias de médias, utilizando o método de Monte Carlo. Foi obtida a amplitude padronizada sob H0, obtida na distribuição a posteriori das médias, contemplando a...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Simulação; Erro tipo I; Poder; Monte Carlo; Não balanceamento.
Ano: 2010 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542010000400008
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Construction et étude d'un modèle de réseau trophique de la vasière de Brouage (bassin de marennes Oléron, France). Prise en compte de la saisonnalité et des échanges physiques pour la synthèse constructive des connaissances sur une zone intertidale d'une région tempérée. ArchiMer
Leguerrier, Dephine.
In order to better understand the functioning of the Brouage intertidal mudflat (Marennes- Oléron Basin, France), its carbon-based trophic web has been modelled and analyzed. The foodweb building is based on the 4 step method of Inverse Analysis: 1) conceive an a priori model as the graph of compartments (nodes) between which exist fluxes of material (vertices). These vertices are the unknowns for the problem; 2) gather all the existing knowledge about the ecosystem and translate it into linear equations and inequalities involving the fluxes; 3) complete this set of data by common knowledge on the behaviour of the compartments and translate it into inequalities, 4) solve the obtained linear system under the parsimony principle to find a unique solution...
Tipo: Text Palavras-chave: Brouage Mudflat; Box Model; Seasonality; Dynamic Model; Static Model; Monte Carlo; Markov Chains; Network Analysis; Intertidal Mudflat; Food Web; Inverse Analysis; Vasière de Brouage; Modèle en boîtes; Saisonnalité; Modèle Dynamique; Modèle Statique; Monte Carlo; Chaînes de Markov; Analyse des Réseaux; Vasière Intertidale; Réseau Trophique; Analyse Inverse.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/2005/these-2260.pdf
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Best practice in Ecopath with Ecosim food-web models for ecosystem-based management ArchiMer
Heymans, Johanna Jacomina; Coll, Marta; Link, Jason S.; Mackinson, Steven; Steenbeek, Jeroen; Walters, Carl; Christensen, Villy.
Ecopath with Ecosim (EwE) models are easier to construct and use compared to most other ecosystem modelling techniques and are therefore more widely used by more scientists and managers. This, however, creates a problem with quality assurance; to address this we provide an overview of best practices for creating Ecopath, models. We describe the diagnostics that can be used to check for thermodynamic and ecological principles, and highlight principles that should be used for balancing a model. We then highlight the pitfalls when comparing Ecopath models using Ecological Network Analysis indices. For dynamic simulations in Ecosim we show the state of the art in calibrating the model by fitting it to time series using a formal fitting procedure and...
Tipo: Text Palavras-chave: Ecopath with Ecosim; Ecological network analysis; Ecosystem modelling; Ecosystem-based management; Monte Carlo; Time series fitting.
Ano: 2016 URL: https://archimer.ifremer.fr/doc/00626/73763/74237.pdf
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Assessing the potential for beneficial diversification in rain-fed agricultural enterprises AgEcon
Kandulu, John.
Climate change and climate variability induce uncertainty in yields, and thus threaten long term economic viability of rain-fed agricultural enterprises. Enterprise mix diversification is the most common, and is widely regarded as the most effective, strategy for mitigating multiple sources of farm business risk. We assess the potential for enterprise mix diversification in mitigating climate induced variability in long term net returns from rain-fed agriculture. We build on APSIM modelling and apply Monte Carlo simulation, probability theory, and finance techniques, to assess the potential for enterprise mix diversification to mitigate climate-induced variability in long term economic returns from rain-fed agriculture. We consider four alternative farm...
Tipo: Conference Paper or Presentation Palavras-chave: Climate variability; Yield uncertainty; Economic returns; Rain-fed agricultural enterprise; Risk; Monte Carlo; Environmental Economics and Policy.
Ano: 2011 URL: http://purl.umn.edu/100568
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Monte Carlo Benchmarks for Discrete Response Valuation Methods AgEcon
Huang, Ju-Chin; Smith, V. Kerry.
This paper argues that the widespread belief that discrete contingent valuation (CV) questions yield substantially larger estimates of the mean (and the median) willingness to pay (WTP) for nonmarket environmental resources in comparison to estimates from open-ended CV questions is unfounded. A set of Monte Carlo experiments estimate the factors influencing the performance of WTP estimates based on discrete response models. Most of the error in the WTP estimates arises from the specification errors that are common in most of the empirical models used in the literature. These experiments suggest models based on choices where WTP is dominated by non use (or passive use) values are likely to have smaller errors than where large use values influence these...
Tipo: Working or Discussion Paper Palavras-chave: Discrete response contingent valuation; Monte Carlo; Non-market valuation; Financial Economics; C93; D12; Q2.
Ano: 1997 URL: http://purl.umn.edu/10546
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Proving causal relationships using observational data AgEcon
Bryant, Henry L.; Bessler, David A..
We describe a means of rejecting a null hypothesis concerning observed, but not deliberately manipulated, variables of the form H0: A -/-> B in favor of an alternative hypothesis HA: A --> B, even given the possibility of causally related unobserved variables. Rejection of such an H0 relies on the availability of two observed and appropriately related instrumental variables. While the researcher will have limited control over the confidence level in this test, simulation results suggest that type I errors occur with a probability of less than 0.15 (often substantially less) across a wide range of circumstances. The power of the test is limited if there are but few observations available and the strength of correspondence among the variables is weak....
Tipo: Conference Paper or Presentation Palavras-chave: Causality; Monte Carlo; Observational data; Hypothesis testing; Research Methods/ Statistical Methods.
Ano: 2011 URL: http://purl.umn.edu/103238
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Multinomial goodness–of–fit: Large–sample tests with survey design correction and exact tests for small samples AgEcon
Jann, Ben.
I introduce the new mgof command to compute distributional tests for discrete (categorical, multinomial) variables. The command supports largesample tests for complex survey designs and exact tests for small samples as well as classic large-sample x2-approximation tests based on Pearson’s X2, the likelihood ratio, or any other statistic from the power-divergence family (Cressie and Read, 1984, Journal of the Royal Statistical Society, Series B (Methodological) 46: 440–464). The complex survey correction is based on the approach by Rao and Scott (1981, Journal of the American Statistical Association 76: 221–230) and parallels the survey design correction used for independence tests in svy: tabulate. mgof computes the exact tests by using Monte Carlo methods...
Tipo: Article Palavras-chave: Mgof; Mgofi; Multinomial; Goodness-of-fit; Chi-squared; Categorical data; Exact tests; Monte Carlo; Exhaustive enumeration; Combinatorial algorithms; Complex survey correction; Power-divergence statistic; Kolmogorov–Smirnov; Benford's law; Research Methods/ Statistical Methods.
Ano: 2008 URL: http://purl.umn.edu/122584
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Economic substitution for US wheat food use by class AgEcon
Marsh, Thomas L..
Wheat for food use is conceptualised as an input into flour production and demand is derived from an industry profit function to quantify price responsiveness and economic substitutability across wheat classes. Price and substitution elasticities are estimated for hard red winter, hard red spring, soft red wheat, soft white winter and durum wheat. In general, hard red winter and spring wheat varieties are much more responsive to their own price than are soft wheat varieties and durum wheat. Substitution elasticities indicate that hard red winter and hard red spring wheat are economic substitutes for milling purposes.
Tipo: Article Palavras-chave: Elasticities; Like product; Monte Carlo; Wheat by class; Crop Production/Industries; Food Consumption/Nutrition/Food Safety.
Ano: 2005 URL: http://purl.umn.edu/118503
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Determining Optimal Levels of Nitrogen Fertilizer Using Random Parameter Models AgEcon
Tumusiime, Emmanuel; Brorsen, B. Wade; Mosali, Jagadeesh; Johnson, Jim; Locke, James; Biermacher, Jon T..
The parameters of yield response functions can vary by year. Past studies usually assume yield functions are nstochastic ‘‘limited’’ stochastic. In this study, we estimate rye– ryegrass yield functions in which all parameters are random. The three functional forms considered are the linear response plateau, the quadratic, and the Spillman-Mitscherlich. Nonstochastic yield models are rejected in favor of stochastic parameter models. Quadratic functional forms fit the data poorly. Optimal nitrogen application recommendations are calculated for the linear response plateau and Spillman-Mitscherlich. The stochastic models lead to smaller recommended levels of nitrogen, but the economic benefits of using fully stochastic crop yield functions are small because...
Tipo: Journal Article Palavras-chave: Cereal rye–ryegrass; Monte Carlo; Nitrogen; Random parameters; Stochastic plateau; Production Economics; Q10; C12; D24.
Ano: 2011 URL: http://purl.umn.edu/117949
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Shade-Grown Coffee: Simulation and Policy Analysis for Coastal Oaxaca, Mexico AgEcon
Batz, Michael B.; Albers, Heidi J.; Avalos-Sartorio, Beatriz; Blackman, Allen.
Shade-grown coffee provides a livelihood to many farmers, protects biodiversity, and creates environmental services. Many shade-coffee farmers have abandoned production in recent years, however, in response to declines in international coffee prices. This paper builds a farmer decision model under price uncertainty and uses simulation analysis of that model to examine the likely impact of various policies on abandonment of shade-coffee plantations. Using information from coastal Oaxaca, Mexico, this paper examines the role of various constraints in abandonment decisions, reveals the importance of the timing of policies, and characterizes the current situation in the study region.
Tipo: Working or Discussion Paper Palavras-chave: Coffee farming; Decision analysis; Numerical modeling; Monte Carlo; Price variability; Crop Production/Industries; O13; Q17; Q12; Q23; Q24.
Ano: 2005 URL: http://purl.umn.edu/10511
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Determining Optimal Levels of Nitrogen Fertilizer Using Random Parameter Models AgEcon
Tumusiime, Emmanuel; Brorsen, B. Wade; Biermacher, Jon T.; Mosali, Jagadeesh; Johnson, Jim; Locke, James.
The parameters of yield response functions can vary by year. Past studies usually assume yield functions are nonstochastic or ‘limited’ stochastic. In this study, we estimate rye-ryegrass yield functions where all parameters are random. Optimal nitrogen rates are calculated for two yield response functions: linear response plateau and quadratic. Nonstochastic models are rejected in favor of stochastic parameter models. However, the economic benefits of using fully stochastic models are small since optimal nitrogen rates do not differ greatly between stochastic and nonstochastic models.
Tipo: Conference Paper or Presentation Palavras-chave: Linear response plateau; Monte Carlo; Nitrogen; Random parameters; Agricultural and Food Policy; Crop Production/Industries; Farm Management; Production Economics.
Ano: 2010 URL: http://purl.umn.edu/56514
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Elasticities for U.S. Wheat Food Use by Class AgEcon
Marsh, Thomas L..
We conceptualize wheat for food use as an input into flour production and derive demand functions to quantify price responsiveness and economic substitutability across wheat classes. Cost, price, and substitution elasticities are estimated for hard red winter, hard red spring, soft red wheat, soft white winter, and durum wheat. In general, hard red winter and spring wheat varieties are much more responsive to their own price than are soft wheat varieties and durum wheat. Morishima elasticities indicate that hard red winter and hard red spring wheat are economic substitutes for milling purposes.
Tipo: Conference Paper or Presentation Palavras-chave: Elasticities; Wheat by class; Economic substitution; Monte Carlo; Food Consumption/Nutrition/Food Safety; C15; C30; Q11.
Ano: 2003 URL: http://purl.umn.edu/57920
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An exact and a Monte Carlo proposal to the Fisher–Pitman permutation tests for paired replicates and for independent samples AgEcon
Kaiser, Johannes.
This article concerns the nonparametric Fisher–Pitman tests for paired replicates and independent samples. After outlining the theory of exact tests, I derive Monte Carlo simulations for both of them. Simulations can be useful if one deals with many observations because of the complexity of the algorithms in regard to sample sizes. The tests are designed to be a more powerful alternative to the Wilcoxon signed-rank test and the Wilcoxon–Mann–Whitney rank-sum test if the observations are given on at least an interval scale. The results gained by Monte Carlo versions of the tests are accurate enough in comparison to the exact versions. Finally, I give examples for using both supplemented tests.
Tipo: Article Palavras-chave: Permtest1; Permtest2; Nonparametric tests; Monte Carlo; Permutation tests; Research Methods/ Statistical Methods.
Ano: 2007 URL: http://purl.umn.edu/119284
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