Case-cohort sampling is a commonly used and efficient method for studying large cohorts.In many situations,some covariates are easily measured on all cohort subjects,and surrogate measurements of the expensive covariates also may be observed.In this paper,to make full use of the covariate data collected outside the case-cohort sample,we propose a class of weighted estimators with general time-varying weights for the additive hazards model,and the estimators are shown to be consistent and asymptotically normal.We also identify the estimator within this class that maximizes efficiency,and simula...
