Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Linear versus nonlinear methods of sire evaluation for categorical traits : a simulation study | Génét. Sél. Evol. 1985 17 1 115-132 Linear versus nonlinear methods of sire evaluation for categorical traits a simulation study A. MEIJERING and D. GIANOLA Department of Animal Science University of Illinois Urbana Illinois 61801 . On leave from Research Institute for Animal Production Schoonoord 3700 AM Zeist The Netherlands Summary Linear BLUP and nonlinear GFCAT methods of sire evaluation for categorical data were compared using Monte Carlo techniques. Binary and ordered tetrachotomous responses were generated from an underlying normal distribution via fixed thresholds so as to model incidences in the population as a whole. Sires were sampled from a normal distribution and family structure consisted of half-sib groups of equal or unequal size simulations were done at several levels of heritability hj . When a one-way model was tenable or when responses were tetrachotomous the differences between the 2 methods were negligible. However when responses were binary the layout was highly unbalanced and a mixed model was appropriate to describe the underlying variate GFCAT elicited significantly larger responses to truncation selection than BLUP at h .20 or .50 and when the incidence in the population was below 25 p. 100. The largest observed difference in selection efficiency between the 2 methods was 12 p. 100. Key words Categorical data sire evaluation threshold traits nonlinear models simulation. Resume Méthodes linéaires et non linéaires d evaluation des pères sur des caractères discrets étude par simulation Des méthodes linéaires BLUP et non linéaires GFCAT d evaluation des pères sur données discretes ont été comparées à 1 aide des techniques de Monte Carlo. On a simulé des réponses selon 2 OU 4 categories à partir d une distribution normale sous-jacente munie de seuils fixes. Les pères ont été échantillonnés dans une distribution normale. La structure famille comportait des groupes de demi-germains de taille égale OU inégale. Les simulations ont été .
