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Registros recuperados: 31 | |
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Puiatti,Guilherme Alves; Cecon,Paulo Roberto; Nascimento,Moysés; Nascimento,Ana Carolina Campana; Carneiro,Antônio Policarpo Souza; Silva,Fabyano Fonseca e; Puiatti,Mário; Cruz,Cosme Damião. |
ABSTRACT: The objective of this study was to adjust nonlinear quantile regression models for the study of dry matter accumulation in garlic plants over time, and to compare them to models fitted by the ordinary least squares method. The total dry matter of nine garlic accessions belonging to the Vegetable Germplasm Bank of Universidade Federal de Viçosa (BGH/UFV) was measured in four stages (60, 90, 120 and 150 days after planting), and those values were used for the nonlinear regression models fitting. For each accession, there was an adjustment of one model of quantile regression (τ=0.5) and one based on the least squares method. The nonlinear regression model fitted was the Logistic. The Akaike Information Criterion was used to evaluate the goodness of... |
Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Quantile regression; Nonlinear regression; Allium sativum L.; Growth rate; Cluster analysis.. |
Ano: 2020 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782020000100203 |
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Puiatti,Guilherme Alves; Cecon,Paulo Roberto; Nascimento,Moysés; Nascimento,Ana Carolina Campana; Carneiro,Antônio Policarpo Souza; Silva,Fabyano Fonseca e; Puiatti,Mário; Oliveira,Ana Carolina Ribeiro de. |
ABSTRACT: Plant growth analyses are important because they generate information on the demand and necessary care for each development stage of a plant. Nonlinear regression models are appropriate for the description of curves of growth, since they include parameters with practical biological interpretation. However, these models present information in terms of the conditional mean, and they are subject to problems in the adjustment caused by possible outliers or asymmetry in the distribution of the data. Quantile regression can solve these problems, and it allows the estimation of different quantiles, generating more complete and robust results. The objective of this research was to adjust a nonlinear quantile regression model for the study of dry matter... |
Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Quantile regression; Nonlinear regression; Dry matter; Allium sativum L. |
Ano: 2018 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782018000100203 |
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Day, Louise; Le Bris, Hervé; Saulnier, Erwan; Pinsivy, Lucas; Brind'Amour, Anik. |
Coastal and estuarine habitats function as nurseries for many commercial marine species. In these ecosystems, the hypothesis that food supply limits juvenile fish density and survival has been widely debated. Direct approaches that test this hypothesis in temperate soft-bottom nurseries are data-intensive as they rely on beam trawl to collect juvenile fish and grab or core to collect their prey within the macrobenthic community. Thus, application has often been limited to a few sampling stations and temporal snapshots. However, scientific beam trawl surveys, conducted periodically in nurseries, sample, besides juvenile fish, benthic invertebrates including potential prey species. Using data collected solely from beam trawl surveys, we tested whether food... |
Tipo: Text |
Palavras-chave: Young-of-the-year fish; Macrobenthic production; Trawl; Grab; Bay of Biscay; Quantile regression. |
Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00600/71239/69607.pdf |
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Chassot, Emmanuel; Bonhommeau, Sylvain; Dulvy, Nicholas K.; Melin, Frederic; Watson, Reg; Gascuel, Didier; Le Pape, Olivier. |
Primary production must constrain the amount of fish and invertebrates available to expanding fisheries; however the degree of limitation has only been demonstrated at regional scales to date. Here we show that phytoplanktonic primary production, estimated from an ocean-colour satellite (SeaWiFS), is related to global fisheries catches at the scale of Large Marine Ecosystems, while accounting for temperature and ecological factors such as ecosystem size and type, species richness, animal body size, and the degree and nature of fisheries exploitation. Indeed we show that global fisheries catches since 1950 have been increasingly constrained by the amount of primary production. The primary production appropriated by current global fisheries is 17-112% higher... |
Tipo: Text |
Palavras-chave: Bottom-up; Large Marine Ecosystem; Quantile regression; Sustainable fishing. |
Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00002/11294/7836.pdf |
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Katchova, Ani L.. |
This study examines the portfolio allocation of assets for farm and nonfarm households using the Agricultural Resource Management Survey and the Survey of Consumer Finances. The stylized facts of household finance, including limited participation in equity markets and heterogeneity of asset portfolios, are also confirmed for farm households. However, farm households show fewer differences in participation rates and asset allocation across wealth groups. Probit and conditional regression models indicate that fewer demographic factors affect participation rates and portfolio shares of risky assets for farm than nonfarm households. The aggregate statistics seem overwhelmingly influenced by households with large holdings of risky assets as shown by quantile... |
Tipo: Journal Article |
Palavras-chave: Farm households; Financial management; Nonfarm households; Portfolio analysis; Quantile regression; Agricultural Finance; Financial Economics. |
Ano: 2008 |
URL: http://purl.umn.edu/48143 |
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Variyam, Jayachandran N.. |
The purpose of this study is to better characterize factors associated with the likelihood of macronutrient excess or inadequacy among U.S adults by modeling parts of the conditional distribution of dietary intakes other than the conditional mean. The risk of dietary inadequacy or excess faced by an individual tends to increase as his or her intake moves from the mean of a nutrient intake distribution toward its tails. Therefore, marginal effects of explanatory variables estimated at the conditional mean using ordinary least squares may be of limited value in characterizing these distributions. Quantile regression is effective in this situation since it can estimate conditional functions at any part of the distribution. Quantile regressions based on data... |
Tipo: Working or Discussion Paper |
Palavras-chave: Diet quality; Health risk; Heteroskedasticity; Nutrition; Quantile regression; Food Consumption/Nutrition/Food Safety. |
Ano: 2003 |
URL: http://purl.umn.edu/33572 |
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Kaditi, Eleni A.; Nitsi, Elisavet I.. |
This paper examines the effects of farm characteristics and government policies in enhancing productivity growth for a sample of Greek farms, using a two-stage procedure. In the 1st-stage, non-parametric estimates of Malmquist index and its decompositions are computed, while a bootstrapping procedure is applied to provide their statistical precision. In the 2nd-stage, the productivity growth estimates are regressed on various covariates using a bootstrapped quantile regression approach. The effect that the covariates exert on productivity growth of the average producer is analyzed, as well as the marginal effect of a given covariate for individuals at different points in the conditional productivity distribution. The results indicate that there exists... |
Tipo: Conference Paper or Presentation |
Palavras-chave: Malmquist productivity index; Quantile regression; Bootstrap; Research Methods/ Statistical Methods; C14; C21; D24. |
Ano: 2009 |
URL: http://purl.umn.edu/52845 |
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Swindall, Devin C.; Willis, David B.; Boys, Kathryn A.; Hughes, David W.. |
Supporters claim that entrepreneurship is critical to building and sustaining the regional economies of urban and rural areas across the nation. Proponents argue that economic development practices that enhance and support entrepreneurship are essential because they cultivate innovation which, in turn, creates new jobs, new wealth, and a better quality of life. However, South Carolina’s real self-employed per capita income has decreased over the last decade. This downward trend highlights the need to examine the drivers of entrepreneurial income. The income of self-employed workers, as opposed to the number of self-employed, is critical to economic development because a major goal of economic policy is to increase incomes not just employment. Identifying... |
Tipo: Conference Paper or Presentation |
Palavras-chave: Self-employed income; Entrepreneurship; Quantile regression; Community/Rural/Urban Development; Consumer/Household Economics; Labor and Human Capital; R11; R12. |
Ano: 2011 |
URL: http://purl.umn.edu/103957 |
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Registros recuperados: 31 | |
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