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Nonlinear quantile regression to describe the dry matter accumulation of garlic plants Ciência Rural
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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Quantile regression of nonlinear models to describe different levels of dry matter accumulation in garlic plants Ciência Rural
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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Suitable habitats of fish species in the Barents Sea ArchiMer
Husson, Berengere; Certain, Gregoire; Filin, Anatoly; Planque, Benjamin.
Many marine species exhibit poleward migrations following climate change. The Barents Sea, a doorstep to the fast‐warming Arctic, is experiencing large scale changes in its environment and its communities. Tracking and anticipating changes for management and conservation purposes at the scale of the ecosystem necessitate quantitative knowledge on individual species distribution drivers. This paper aims at identifying the factors controlling demersal habitats in the Barents Sea, investigating for which species we can predict current and future habitats and inferring those most likely to respond to climate change. We used non‐linear quantile regressions (QGAM) to model the upper quantile of the biomass response of 33 fish species to 10 environmental...
Tipo: Text Palavras-chave: Climate change; Environmental niche; Generalized additive models; Habitat suitability models; Limiting factors; Quantile regression; Species distribution.
Ano: 2020 URL: https://archimer.ifremer.fr/doc/00641/75352/76099.pdf
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Suitable habitats of fish species in the Barents Sea ArchiMer
Husson, Berengere; Certain, Gregoire; Filin, Anatoly; Planque, Benjamin.
Many marine species are shifting their distribution poleward in response to climate change. The Barents Sea, as a doorstep to the fast-warming Arctic, is experiencing large scale changes in its environment and its communities. This paper aims at understanding what environmental predictors limit fish species habitats in the Barents Sea and discuss their possible evolution in response to the warming of the Arctic. Species distribution models usually aim at predicting the probability of presence or the average abundance of a species, conditional on environmental drivers. A complementary approach is to determine suitable habitats by modelling the upper limit of a species’ response to environmental factors. Using quantile regressions, we model the upper limit...
Tipo: Text Palavras-chave: Quantile regression; Habitat suitability models; Climate change; Species distribution; Species shifts; Environmental drivers.
Ano: 2020 URL: https://archimer.ifremer.fr/doc/00605/71682/70120.pdf
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Benthic prey production index estimated from trawl survey supports the food limitation hypothesis in coastal fish nurseries ArchiMer
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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Global marine primary production constrains fisheries catches ArchiMer
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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The Effect of Prior Gains and Losses on Current Risk-Taking Using Quantile Regression AgEcon
Mattos, Fabio; Garcia, Philip.
This paper investigates the dynamics of sequential decision-making in agricultural futures and options markets using a quantile regression framework. Analysis of trading records of 12 traders suggests that there is great heterogeneity in individual trading behavior. Traders respond differently to prior profits depending on how much risk their portfolios are carrying. In general, no significant response is found at average and below-average levels of risk, but response can become large and significant at above-average levels of risk. These results are consistent with studies which argued that behavior may be uneven under different circumstances, and calls into question the adoption of conditional mean framework to investigate trading behavior. Focusing the...
Tipo: Conference Paper or Presentation Palavras-chave: Loss aversion; House-money effect; Quantile regression; Futures; Options; Agribusiness; Agricultural Finance; Consumer/Household Economics; Demand and Price Analysis; Farm Management; Financial Economics; Marketing; Research Methods/ Statistical Methods; Risk and Uncertainty.
Ano: 2009 URL: http://purl.umn.edu/53035
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Agglomeration, Spatial Interaction and Convergence in the EU AgEcon
Brauninger, Michael; Niebuhr, Annekatrin.
We investigate the convergence process among EU regions between 1980-2002 taking into account the effects of spatial heterogeneity and spatial spillover effects. The spatial regimes model allows for different steady-state growth paths. In contrast to previous analyses, the regimes in this paper refer to spatial categories, i.e. we assume that agglomerations, urbanised and rural regions are characterised by group-specific steadystates. Moreover, the regression analysis considers the effects of interaction among neighbouring regions, possibly leading to a spatial dependence of regional growth rates. We check whether spatial dependence is caused by spatial spillovers or based on country effects.
Tipo: Working or Discussion Paper Palavras-chave: Convergence; Agglomeration; European Union; Spatial econometrics; Quantile regression; International Development; C21; O52; R11.
Ano: 2005 URL: http://purl.umn.edu/26150
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Financial Management and Portfolio Analysis for U.S. Farm and Nonfarm Households AgEcon
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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Food Security and Wheat Prices in Afghanistan: A Distribution-sensitive Analysis of Household-level Impacts AgEcon
D'Souza, Anna; Jolliffe, Dean.
Replaced with revised version of paper 07/29/11.
Tipo: Conference Paper or Presentation Palavras-chave: Afghanistan; Food prices; Wheat; Food security; Nutrition; Poverty; Quantile regression; Influence functions; Consumer/Household Economics; Food Consumption/Nutrition/Food Safety; Food Security and Poverty; D12; I3.
Ano: 2011 URL: http://purl.umn.edu/103443
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Does Gibrat's Law Hold Amongst Dairy Farmers in Northern Ireland? AgEcon
Kostov, Philip; Patton, Myles; Moss, Joan E.; McErlean, Seamus.
This paper tests whether the Law of Proportionate Effects (Gibrat, 1931), which states that farms grow at a rate that is independent of their size, holds for the dairy farms in Northern Ireland. Previous studies have tended to concentrate on testing whether the law holds for all farms. The methodology used in this study permits investigation of whether the law holds for some farms or all farms according to their size. The approach used avoids the subjective splitting of samples, which tends to bias results. The finding shows that the Gibrat law does hold except in the case of small farms. This is in accordance with previous findings that Gibrat's law tends to hold when only larger farms are considered, but tends to fail when smaller farms are included in...
Tipo: Conference Paper or Presentation Palavras-chave: Gibrat's law; Quantile regression; Sample selection bias; Integrated Conditional Moments test; Agricultural and Food Policy; C12; C14; O49; Q19.
Ano: 2005 URL: http://purl.umn.edu/24775
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The Changing Structure of Commercial Banks Lending to Agriculture AgEcon
Nam, Sangjeong; Ellinger, Paul N.; Katchova, Ani L..
Replaced with revised version of paper 06/11/07.
Tipo: Conference Paper or Presentation Palavras-chave: Agricultural loan; Agricultural loan growth; Quantile regression; Agricultural Finance.
Ano: 2007 URL: http://purl.umn.edu/9913
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Impact of Off-farm Income on Farm Efficiency in Slovenia AgEcon
Bojnec, Stefan; Ferto, Imre.
Impact of Off-farm Income on Farm Efficiency in Slovenia
Tipo: Conference Paper or Presentation Palavras-chave: Off-farm income; Stochastic frontier analysis; Panel regression; Quantile regression; Slovenia; Agricultural Finance; Farm Management.
Ano: 2011 URL: http://purl.umn.edu/114258
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Analyzing the Determinants of Technical Efficiency Among Traditional Dairy Farms in Wisconsin: A Quantile Regression Approach AgEcon
Chidmi, Benaissa; Solis, Daniel; Funtanilla, Margil; Cabrera, Victor E..
This study analyzes the determinants of TE among traditional dairy farms in the State of Wisconsin taking into account dairy farms’ heterogeneity. To do so, we first estimate a production frontier and the level of TE using the SPF framework. Then we analyze the determinants of TI using a quantile regression analysis. The results indicate that the determinants of TE affect in very specific ways farmers with different levels of TE. This result confirms our hypothesis on the importance of controlling for farm heterogeneity when analyzing the determinants of TE. This issue is also important from an empirical point of view. Policy makers could improve the effectiveness of their work by targeting specific agricultural services and aid designed for farmers with...
Tipo: Conference Paper or Presentation Palavras-chave: Technical efficiency; Dairy; Quantile regression; Agribusiness; Agricultural and Food Policy; Marketing; Production Economics; Productivity Analysis.
Ano: 2010 URL: http://purl.umn.edu/61320
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Factors Affecting the Macronutrient Intake of U.S. Adults AgEcon
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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A two-stage productivity analysis using bootstrapped Malmquist index and quantile regression AgEcon
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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The Impact of Human Capital on Farm Operator Household Income AgEcon
El-Osta, Hisham S..
Data from the 2006 Agricultural Resource Management Survey and multivariate regression procedures are used to examine the role of human capital in impacting the incomes of farm households. The paper uses an “adjusted” concept of income where government payments are subtracted from total household income thus allowing for the utilization of government payments as a potential control variable in the regression models. Findings indicate a significant and positive role for higher education except for farm households at the very lower and upper ends of the income distribution.
Tipo: Journal Article Palavras-chave: Farm households; ARMS data; Quantile regression; Government payments; Human capital; Off-farm wages and salaries; Agricultural Finance; Consumer/Household Economics; Farm Management; Financial Economics; Labor and Human Capital.
Ano: 2011 URL: http://purl.umn.edu/106062
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The Determinants of Self-Employed Income in a Regional Economy AgEcon
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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Changes in Fruit and Vegetable Consumption over Time and across Regions in China: A Difference-in-Differences Analysis with Quantile Regression AgEcon
Liu, Kang Ernest; Chang, Hung-Hao; Chern, Wen S..
Recently, there has been considerable interest in estimating food demand structure in China due to its huge market for food products. Previous literature has focused on the primary food products such as grains and meats, but studies on fruits and vegetables are limited. To fulfill this gap, this paper investigates the changes of fruit and vegetable consumption in Chinese urban households between 1993 and 2001. In this study, we use the difference-in-differences method with quantile regression to demonstrate how these changes of fruit and vegetable consumption over time may differ across regions. Additionally, how these changes may differ over the entire distribution. Using household survey data from 1993 and 2001 of three selected provinces, our results...
Tipo: Conference Paper or Presentation Palavras-chave: Fruit and vegetable consumption; China; Inequality; Quantile regression; Difference-in-differences model.; Food Consumption/Nutrition/Food Safety.
Ano: 2008 URL: http://purl.umn.edu/6531
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Trade and Intellectual Property Rights in the Agricultural Seed Sector AgEcon
Eaton, Derek J.F..
The Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS) has continued to be fiercely debated between North and South, particularly with respect to its provisions for the agricultural sector. Article 27.3(b) of the TRIPS Agreement requires WTO member countries to offer some form of intellectual property protection for new plant varieties, either in the form of patents (common in the U.S.) or plant breeder’s rights (PBR). This paper analyses the effects of the introduction of PBRs in almost 70 importing countries on the value of exports of agricultural seeds and planting material from 10 exporting EU countries, including all principal traditional exporters of seeds, as well as the US. A fixed effects quantile regression model, based on...
Tipo: Conference Paper or Presentation Palavras-chave: Intellectual property rights; Trade; Agriculture; Plant breeding; Quantile regression; Agricultural and Food Policy; Industrial Organization; International Relations/Trade; Q16; Q17; F13; F14.
Ano: 2009 URL: http://purl.umn.edu/51782
Registros recuperados: 31
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