Sabiia Seb
PortuguêsEspañolEnglish
Embrapa
        Busca avançada

Botão Atualizar


Botão Atualizar

Ordenar por: 

RelevânciaAutorTítuloAnoImprime registros no formato resumido
Registros recuperados: 3
Primeira ... 1 ... Última
Imagem não selecionada

Imprime registro no formato completo
Testing Day’s Conjecture that More Nitrogen Decreases Crop Yield Skewness AgEcon
Du, Xiaodong; Hennessy, David A.; Yu, Cindy L..
While controversy surrounds skewness attributes of typical yield distributions, a better understanding is important for agricultural policy assessment and for crop insurance rate setting. Day (1965) conjectured that crop yield skewness declines with an increase in low levels of nitrogen use, but higher levels have no effect. In a theoretical model based on the law of the minimum (von Liebig) technology, we find conditions under which Day’s conjecture applies. Employing four experimental plot datasets, we investigate the conjecture by introducing (a) a flexible Bayesian extension of the Just-Pope technology to incorporate skewness, and (b) a quantile-based measure of skewness shift. For corn yields, the Bayesian estimation provides strong evidence in favor...
Tipo: Working or Discussion Paper Palavras-chave: Crop insurance; Gibbs sampler; Just and Pope technology; Negative skewness; Quantile regression.; Crop Production/Industries; Political Economy; Research Methods/ Statistical Methods; Risk and Uncertainty.
Ano: 2010 URL: http://purl.umn.edu/93471
Imagem não selecionada

Imprime registro no formato completo
Toward a Normative Theory of Crop Yield Skewness AgEcon
Hennessy, David A..
While the preponderance of empirical studies point to negative crop yield skewness in a wide variety of contexts, the literature provides few clear insights on why this is so. The purpose of this paper is to make three points on the matter. We show formally that statistical laws on aggregates do not suggest a normal yield distribution. We explain that whenever the weather-conditioned mean yield has diminishing marginal product, then there is a disposition toward negative skewness in aggregate yields. This is because a high marginal product in bad weather states stretches out the left tail of the yield distribution relative to that of the weather distribution. Turning to disaggregated yields, we decompose unconditional skewness into weather-conditioned...
Tipo: Working or Discussion Paper Palavras-chave: Conditional distribution; Crop insurance; Negative skewness; Spatial heterogeneity; Statistical laws..
Ano: 2008 URL: http://purl.umn.edu/37548
Imagem não selecionada

Imprime registro no formato completo
Crop Yield Skewness and the Normal Distribution AgEcon
Hennessy, David A..
Empirical studies point to negative crop yield skewness, but the literature provides few clear insights as to why. This paper formalizes three points on the matter. Statistical laws on aggregates do not imply a normal distribution. Whenever the weather-conditioned mean yield has diminishing marginal product with respect to a weather-conditioning index, then there is a disposition toward negative yield skewness. This is because high marginal product in bad weather stretches out the yield distribution's left tail relative to that for weather. For disaggregated yields, unconditional skewness is decomposed into weather-conditioned skewness plus two other terms and each is studied in turn.
Tipo: Journal Article Palavras-chave: Conditional distribution; Crop insurance; Negative skewness; Normal distribution; Statistical laws; Crop Production/Industries; Risk and Uncertainty.
Ano: 2009 URL: http://purl.umn.edu/50084
Registros recuperados: 3
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