TY - JOUR

T1 - Effects of mid‐point imputation on the analysis of doubly censored data

AU - Law, C. Gordon

AU - Brookmeyer, Ron

PY - 1992

Y1 - 1992

N2 - Doubly censored data arise in some cohort studies of the AIDS incubation period because the time of infection may be known only up to an interval defined by two successive screening tests for HIV antibody. A simple analytic approach is to impute the infection time by the mid‐point of the interval and then apply standard survival techniques for right censored data. The objective of this paper is to investigate the statistical properties of such a mid‐point imputation approach. We investigated the asymptotic bias of the Kaplan‐Meier estimate, coverage probabilities of associated confidence intervals, bias in hazard ratio, and the size of the logrank test. We show that the statistical properties of mid‐point imputation depend strongly on the underlying distributions of infection times and the incubation periods, and the width of the interval between screening tests. In the absence of treatment, the median incubation period of HIV infection is approximately 10 years, and we conclude that, for this situation, mid‐point imputation is a reasonable procedure for interval widths of 2 years or less.

AB - Doubly censored data arise in some cohort studies of the AIDS incubation period because the time of infection may be known only up to an interval defined by two successive screening tests for HIV antibody. A simple analytic approach is to impute the infection time by the mid‐point of the interval and then apply standard survival techniques for right censored data. The objective of this paper is to investigate the statistical properties of such a mid‐point imputation approach. We investigated the asymptotic bias of the Kaplan‐Meier estimate, coverage probabilities of associated confidence intervals, bias in hazard ratio, and the size of the logrank test. We show that the statistical properties of mid‐point imputation depend strongly on the underlying distributions of infection times and the incubation periods, and the width of the interval between screening tests. In the absence of treatment, the median incubation period of HIV infection is approximately 10 years, and we conclude that, for this situation, mid‐point imputation is a reasonable procedure for interval widths of 2 years or less.

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U2 - 10.1002/sim.4780111204

DO - 10.1002/sim.4780111204

M3 - Article

C2 - 1439361

AN - SCOPUS:0026485594

VL - 11

SP - 1569

EP - 1578

JO - Statistics in Medicine

JF - Statistics in Medicine

SN - 0277-6715

IS - 12

ER -