AGRADECIMENTOSAos meus pais Roque e Inêz, e a minha irmã Silvia, por serem tão presentes na minha vida.A minha tia "Dada", pelo carinho e pela ajuda.Aos meus avós Argemiro (in memorian) e Dirce (Lolinha) (in memorian) por todo carinho.Aos animais que sempre farão parte da minha vida: Lana, Nina, Guinho, Xuxa, Pitu, Pretinha, Virinha, Pitoca entre tantos outros. Obrigada por tornarem minha vida melhor.Aos professores do Departamento de Medicina Social da FMRP por contribuírem para minha formação.Aos funcionários do Departamento de Medicina Social da FMRP pela ajuda com todos os procedimentos burocráticos.Aos meus amigos da FMVZ-USP (alunos, funcionários e professores) pelos anos de convivência e de amizade. Aos meus amigos "dinos" da USP Jr pelos ensinamentos e pelo agradável convívio. Aos funcionários Cristina e Robson da Biblioteca Central da USP Ribeirão Preto pela ajuda com as referências. Aos meus colegas de trabalho da Ourofino. À Ourofino pela concessão dos dados. Palavras-chave: período de carência; regressão linear; regressão; resíduo de medicamento. ABSTRACT ROSA SC. Estimation of the withdrawal period for veterinary drugs in edible tissues of animal origin by regression models. 2016. 288p. Dissertation (Master Degree). Faculty of Medicine of Ribeirao Preto, University of São Paulo, Ribeirão Preto.Veterinary drugs residues can be found in foodstuffs of animal origin such as meat, milk, eggs and honey. In order to ensure that the concentration of these residues does not exceed a safe limit (Maximum Residue Limit -MRL) it is necessary to establish a withdrawal period, which is the waiting time necessary for an animal to be sent for slaughtering after having received a veterinary drug. The estimation of the withdrawal period is normally obtained by the fitting of a simple linear regression model, followed by the calculation of a tolerance limit. For this, the assumptions of homoscedasticity and the normality of the errors must be met. However, violations of these assumptions are frequent in the residual depletion studies. In the present study two database of the quantification of veterinary drug residue in bovine tissues were used and the withdrawal period was estimated for liver, fat, muscle and kidneys. The regression models were fitted to the mean value of the results obtained for each animal, to the mean value of the results obtained for each analytical extraction and to the results obtained for the repeated sample measurements, and a linear mixed model was fitted for this later situation.The linear model fitted to the mean value of the results obtained for each analytical extraction showed greater precision in the parameters estimates of the model as well as shorter withdrawal period. However, for this model, more potentially influential points were detected compared to other models fitted. It was not possible to calculate the tolerance limit, and, consequently, to predict the withdrawal period using the mixed effects model. In conclusion, the fitting of the other more robust and flexible statistical m...