tailieunhanh - Báo cáo sinh học: "Bayesian analysis of calving ease and birth weights"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Bayesian analysis of calving ease and birth weights | Genet Sei Evol 1997 29 117-143 @ Elsevier INRA 117 Original article Bayesian analysis of calving ease scores and birth weights cs Wang RL Quaas EJ Pollak Morrison Hall Department of Animal Science Cornell University Ithaca NY 14853 USA Received 3 January 1996 accepted 13 February 1997 Summary - In a typical two stage procedure breeding value prediction for calving ease in a threshold model is conditioned on estimated genetic and residual covariance matrices. These covariance matrices are traditionally estimated using analytical approximations. A Gibbs sampler for making full Bayesian inferences about fixed effects breeding values thresholds and genetic and residual covariance matrices to analyze jointly a discrete trait with multiple ordered categories calving ease scores and a continuously Gaussian distributed trait birth weights is described. The Gibbs sampler is implemented by drawing from a set of densities - truncated normal uniform and inverted Wishart -making implementation of Gibbs sampling straightforward. The method should be useful for estimating genetic parameters based on features of their marginal posterior densities taking into full account uncertainties in estimating other parameters. For routine large-scale estimation of location parameters breeding values Gibbs sampling is impractical. The joint posterior mode given the posterior mean estimates of thresholds and dispersion parameters is suggested. An analysis of simulated calving ease scores and birth weights is described. dystocia beef cattle threshold model Bayesian method Gibbs sampling Resume Analyse bayésienne des notes de diíĩìcultés de vêlage et des poids de naissance. Dans une procedure typique à deux étapes I evaluation génétique pour la difficulte de vêlage dans un modèle à seuil est conditionnée par les matrices de covariance génétiques et résiduelles. Ces matrices de covariance sont habituellement estimées au travers d approximations analytiques. On décrit 1 échantillonnage de Gibbs .