TAILIEUCHUNG - Báo cáo khoa hoc:" A quasi-score approach to the analysis of ordered categorical data via a mixed heteroskedastic threshold model"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học thế giới đề tài: A quasi-score approach to the analysis of ordered categorical data via a mixed heteroskedastic threshold model | . . ỉ 5 SEPT ỉE Départernent de Génétlqlie Animate BIBLIOTHÉQUE Genet. Sei. Evol. 31 1999 301-318 F - 78352 JOUY EN JOSASCEDEX 301 Inra Elsevier Paris Original article A quasi-score approach to the analysis of ordered categorical data via a mixed heteroskedastic threshold model Florence Jaffrezic Christèle Robert-Granié Jean-Louis Foulley Station de génétique quantitative et appliquée Institut national de la recherche agronomique Centre de recherches de Jouy-en-Josas 78352 Jouy-en-Josas cedex France Received 15 December 1998 accepted 21 April 1999 Abstract - This article presents an extension of the methodology developed by Gilmour et al. 19 for ordered categorical data taking into account the heterogeneity of residual variances of latent variables. Heterogeneity of residual variances is described via a structural linear model on log-variances. This method involves two main steps i a marginalization with respect to the random effects leading to quasi-score estimators ii an approximation of the variance-covariance matrix of the observations which leads to an analogue of the Henderson mixed model equations for continuous Gaussian data. This methodology is illustrated by a numerical example of footshape in sheep. Inra Elsevier Paris generalized linear mixed models quasi-score heterogeneity of variances threshold response model Resume Une approche de quasi-score pour 1 analyse de variables qualitatives ordonnées par un modèle mixte à seuils hétéroscédastique. Cet article présente une extension de la méthodologie développée par Gilmour et al. 19 dans le cas de variables qualitatives ordonnées prenant en compte 1 hétérogénéité des variances residuelies des variables latentes. L hétérogénéité des variances résiduelles est décrite par un modèle linéaire structurel sur les logarithmes des variances. Cette methode comprend deux étapes principales i une marginalisation par rapport aux effets aléatoires qui conduit grace aux equations de quasi-score à 1 estimation

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