Survival analysis

Abstract

Survival is one of the most important functional economic traits in livestock production, affecting profitability through the rate of replacement and farm production levels. This chapter initially introduces some basic concepts associated with survival traits such functional survival and censoring. The various models applied for the analysis of survival traits such as linear and random regression models are subsequently discussed. However, given the peculiarities associated with survival traits in terms of censoring of records and the presence of time-dependent covariates, the proportional hazard model has been considered a more appropriate method of handling such traits. The proportional hazard model is then introduced, examining various distribution and its extension to include random effects such as genetic effects usually called frailty models or mixed survival models.