Alice Liu of the Department of Biostatistics defends her dissertation on "Efficient Estimation of the Quantile Residual Lifetime Using Auxiliary Covariates"
Graduate faculty of the University and all other interested parties are invited to attend.
Quantile residual lifetime (QRL) is of significant interest in many clinical studies as an easily interpretable quantity compared to other summary measures of survival distributions. In cancer or other fatal diseases, treatments are often compared based on the distributions or quantiles of the residual lifetime. For experimental designs, such as for randomized control trials, there is often no interest or need to adjust for the confounding factors due to the nature of the randomization. However, when there is missing data, adding the covariate information can help in improving the efficiency of estimators, e.g., the estimated treatment effect. In this study, we proposed an augmented inverse probability weighting estimator (AIPW) for QRL by incorporating the auxiliary covariate information in the presence of right-censoring. Simulation studies shows that our proposed estimator has smaller variance compared to the inverse probability estimator (IPW) and the Kaplan-Meier type estimator for the QRL when the auxiliary covariate is related to the survival outcome. In contrast, there is minimal efficiency gain over our previously proposed test of equality of two QRLs when using the AIPW estimator compared to the IPW or Kaplan-Meier type estimators.