TAILIEUCHUNG - Báo cáo sinh học: " Bias and sampling covariances of estimates of variance components due to maternal effects"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Bias and sampling covariances of estimates of variance components due to maternal effects | Genet Sei Evol 1992 24 487-509 Elsevier INRA 487 Original article Bias and sampling covariances of estimates of variance components due to maternal effects K Meyer Edinburgh University Institute for Cell Animal and Population Biology West Mains Road Edinburgh EH9 3JT Scotland UK University of New England Animal Genetics and Breeding Unit Armidale NSW 2351 Australia Received 13 September 1991 accepted 26 August 1992 Summary - The sampling behaviour of Restricted Maximum Likelihood estimates of co variance components due to additive genetic and environmental maternal effects is examined for balanced data with different family structures. It is shown that sampling correlations between estimates are high and that sizeable data sets are required to allow reasonably accurate estimates to be obtained even for designs specifically formulated for the estimation of maternal effects. Bias and resulting mean square error when fitting the wrong model of analysis are investigated showing that an environmental dam-offspring covariance which is often ignored in the analysis of growth data for beef cattle has to be quite large before its effect is statistically significant. The efficacy of embryo transfer in reducing sampling correlations direct and maternal genetic co variance components is illustrated. maternal effect variance component I sampling covariance Resume Biais et covariances d echantillonnage des estimées de composantes de variance dues à des effets maternels. Les propriétés d echantillonnage des estimées du maximum de vraisemblance restreint des variances-covariances dues à des effets matemels génétiques additifs et de milieu sont examinees sur des données d un dispositif équilibré et avec differentes structures familiales. On montre que les correlations d echantillonnage en-tre les estimées sont élevées et qu un volume de données important est requis pour obtenir des estimées raisonnablement précises mane avec des dispositifs établis specifiquement pour estimer des .

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