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A weighted AMMI algorithm for nonreplicated data PAB
Assis,Tatiana Oliveira Gonçalves de; Dias,Carlos Tadeu dos Santos; Rodrigues,Paulo Canas.
Abstract: The objective of this work was to propose a weighting scheme for the additive main effects and multiplicative interactions (AMMI) model, as well as to assess the usefulness of this W-AMMI model in the study of genotype x environment interaction (GxE) and quantitative trait locus x environment interaction (QxE) for nonreplicated data. Data from the 'Harrington' x TR306 barley (Hordeum vulgare) mapping population, with 141 genotypes evaluated in 25 environments, were used to compare the results from the AMMI model with those of two proposed versions of the W-AMMI model: equal weights per row and equal weights per column. The proposed W-AMMI columns algorithm is viable to analyze data with heterogeneous variance, when there are no replicates...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Hordeum vulgare; Contaminated data; Genotype-by-environment interaction; Missing data; Outliers; QTL detection.
Ano: 2018 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2018000500557
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Contemporary groups in the genetic evaluation of Nellore cattle using Bayesian inference PAB
Silva,Delvan Alves da; Silva,Fabyano Fonseca e; Ventura,Henrique Torres; Junqueira,Vinícius Silva; Silva,Alessandra Alves da; Mota,Rodrigo Reis; Lopes,Paulo Sávio.
Abstract: The objective of this work was to evaluate the criteria for the formation of contemporary groups (CGs) in the genetic evaluation of body weight at weaning in Nellore cattle. A total of 713,474 records from 3,066 herds located in Midwestern and Northern Brazil were used. Data were obtained from the genealogical registry of zebu breeds of the Brazilian association of zebu breeders. Data structures were defined based on the number of standard deviations (SDs) for outlier removal (±2.0, ±2.5, ±3.0, and ±3.5) and on the minimal number of animals per CG (3, 7, and 15). Genetic evaluation was performed with an animal model using Bayesian inference. Data structures with ±3.5 SDs and CG with at least 15 animals presented the highest additive genetic...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Heritability; Outliers; Zebu..
Ano: 2017 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2017000800643
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Detecting outliers in species distribution data: Some caveats and clarifications on a virtual species study ArchiMer
Meynard, Christine N.; Kaplan, David; Leroy, Boris.
Liu et al. (2018) used a virtual species approach to test the effects of outliers on species distribution models. In their simulations, they applied a threshold value over the simulated suitabilities to generate the species distributions, suggesting that using a probabilistic simulation approach would have been more complex and yield the same results. Here, we argue that using a probabilistic approach is not necessarily more complex and may significantly change results. Although the threshold approach may be justified under limited circumstances, the probabilistic approach has multiple advantages. First, it is in line with ecological theory, which largely assumes non‐threshold responses. Second, it is more general, as it includes the threshold as a...
Tipo: Text Palavras-chave: ENM; Observation errors; Outliers; Prevalence; Probabilistic approach; Sample bias; Simulations; Species distribution models; Virtual ecology; Virtual species.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00501/61309/64868.pdf
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Exportacion de un tomate en Canarias: un patron estacional estable? AgEcon
Rodriguez, Gloria Martin; Cano, Victor; Hernandez, Jose Juan Caceres.
RESUMEN: En este trabajo se analiza el patrón estacional de la exportación semanal de tomate canario desde el ingreso de España en la Unión Europea. Un primer examen de los componentes determinísticos de la serie revela la inestabilidad de éstos, claramente vinculada a los cambios en la normativa comercial de acceso a los mercados europeos, así como la presencia de numerosas observaciones anómalas causadas por fenómenos de diversa índole. Estas circunstancias afectan al estudio detallado de la estacionalidad estocástica de la serie bajo estudio, que reúne dos características —la frecuencia semanal de las observaciones y la existencia de períodos sin exportación— cuya consideración es imprescindible para recoger apropiadamente la conducta de las...
Tipo: Journal Article Palavras-chave: Tomato exports; Seasonality; Unit roots; Structural time series models; Outliers; Crop Production/Industries; Q17.
Ano: 2002 URL: http://purl.umn.edu/28763
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Least likely observations in regression models for categorical outcomes AgEcon
Freese, Jeremy.
This article presents a method and program for identifying poorly fitting observations for maximum-likelihood regression models for categorical dependent variables. After estimating a model, the program least likely will list the observations that have the lowest predicted probabilities of observing the value of the outcome category that was actually observed. For example, when run after estimating a binary logistic regression model, least likely will list the observations with a positive outcome that had the lowest predicted probabilities of a positive outcome and the observations with a negative outcome that had the lowest predicted probabilities of a negative outcome. These can be considered the observations in which the outcome is most surprising given...
Tipo: Journal Article Palavras-chave: Outliers; Predicted probabilities; Categorical dependent variables; Logistic regression; Research Methods/ Statistical Methods.
Ano: 2002 URL: http://purl.umn.edu/116014
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Local influence when fitting Gaussian spatial linear models: an agriculture application Ciencia e Investigación Agraria
Grzegozewski,Denise M; Uribe-Opaz,Miguel A; De Bastiani,Fernanda; Galea,Manuel.
D.M. Grzegozewski, M.A. Uribe-Opazo, F. De Bastiani, and M. Galea. 2013. Local influence when fitting Gaussian spatial linear models: an agriculture application. Cien. Inv. Agr. 40(3): 523-535. Outliers can adversely affect how data fit into a model. Obviously, an analysis of dependent data is different from that of independent data. In the latter, i.e., in cases involving spatial data, local outliers can differ from the data in the neighborhood. In this article, we used the local influence technique to identify influential points in the response variables using two different schemes of perturbations. We applied this technique to soil chemical properties and soybean yield. We evaluated the effects of the influential points on the spatial model selection,...
Tipo: Journal article Palavras-chave: Geostatistical; Influence diagnostics; Maximum likelihood; Outliers; Spatial variability.
Ano: 2013 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-16202013000300006
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Metodologia para análise de adaptabilidade e estabilidade por meio de regressão quantílica PAB
Barroso,Laís Mayara Azevedo; Nascimento,Moysés; Nascimento,Ana Carolina Campana; Silva,Fabyano Fonseca e; Cruz,Cosme Damião; Bhering,Leonardo Lopes; Ferreira,Reinaldo de Paula.
O objetivo deste trabalho foi desenvolver e validar uma metodologia de análise da adaptabilidade e da estabilidade fenotípica baseada em regressão quantílica (RQ). Para tanto, foram simulados valores fenotípicos com distribuição simétrica e com distribuição assimétrica à direita e à esquerda, com ou sem a presença de "outliers". A metodologia proposta foi aplicada a um conjunto de dados provenientes de um experimento com 92 genótipos de alfafa (Medicago sativa), avaliados em 20 ambientes, e comparada às metodologias de Eberhart & Russell e de regressão não paramétrica. A metodologia da RQ proporcionou resultados iguais ou superiores aos obtidos com as metodologias alternativas avaliadas. No entanto, a ocorrência de resultados discordantes entre as...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Medicago sativa; Distribuição assimétrica; Interação genótipo x ambiente; Melhoramento vegetal; Outliers; Regressão não paramétrica..
Ano: 2015 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2015000400290
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