Final Report: Surveys and Investigations Projects as Required by Federal Aid inWildlife Restoration Act, Missouri. Study No. 6. Development of the Cox Proportional Hazard Model for Staggered Entry. Job No. 1

摘要

Understanding the effect of factors that influence survival of a wildlifepopulation is important to wildlife managers. Managers can influence the survival rate of a wildlife population through hunting regulations, habitat management, or by attempting to control other factors, such as disease, predation, and accidents. The Cox proportional hazards model (Cox 1972) is an analytical technique for determining if characteristics of individual animals (such as weight, age, gender, treatment assignment, etc.) influence the probability of survival. These covariates can be either continuous or discrete. An generalized Cox proportional hazards model approach developed by Andersen and Gill (1982) was explored for implementation in the analysis of individuals that enter a study in staggered order. This analytical technique can be used like the staggered entry approach for Kaplan-Meier product limit estimation for telemetry studies (Pollock et al. 1989).