Efficiency Considerations in the Additive Hazards Model with Current Status Data

For current status data, L IN , O AKES and Y ing (1998) proposed a procedure for estimation of the regression parameters in the additive hazards model that makes clever use of martingale theory. However, one of the outstanding problems posed in the paper was the issue of efficient estimation, as their estimators do not attain the semiparametric information bound. In this paper, we explore this issue and provide a characterization of the NPMLE. We conduct efficiency comparisons between the NPMLE and the procedure of L IN et al . (1998) analytically and numerically through analysis of a dataset from a tumorigenicity experiment.