Interval‐censored survival time data: confidence intervals for the non‐parametric survivor function

Abstract
Survival data are described as interval censored when the failure time is not measured exactly but is known only to have occurred within a defined interval. In this paper, we describe and assess three methods for calculating pointwise confidence intervals for the non‐parametric survivor function estimated from interval‐censored data: the first based on the full information matrix, the second a modification of this approach involving deletion of rows and columns of the information matrix corresponding to zero estimates prior to inversion and the third based on likelihood ratio inference. In a simulation study the likelihood ratio method gave the most accurate confidence intervals with coverage consistently close to the nominal level of 95 per cent. Copyright © 2004 John Wiley & Sons, Ltd.