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A series of two-sample non-parametric tests of quantile residual lifetime

Liu, Yimeng (2017) A series of two-sample non-parametric tests of quantile residual lifetime. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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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. Thus a common problem of interest is to test the equality of the QRL between two populations.
In the first chapter of this dissertation, we propose two classes of tests to compare two QRLs; one class is based on the difference between two estimated QRLs, and the other is based on the estimating function of the QRL, where the estimated QRL from one sample is plugged into the QRL-estimating-function of the other sample. We outline the asymptotic properties of the pro-posed test statistics. Simulation studies demonstrate that the proposed tests produced Type I errors closer to the nominal level and are superior to some existing tests based on both Type I error and power. Our proposed statistics are also computationally less intensive and more straightforward compared to tests based on the confidence intervals.
Moreover, 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 the second chapter, we propose 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 associated with 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. We applied the proposed methods to a randomized multicenter Phase III trial for breast cancer patients with positive lymph nodes.
The public health significance of this dissertation is that it provides new methods to estimate and compare the QRLs of the time to event data, that can be used in in epidemiological and clinical studies to estimate and test QRLs more efficiently. This will help make superior inference of the survival outcome in future randomized clinical trials and the observational studies.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Liu, Yimengyil103@pitt.eduyil103
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairWahed, Abdus S.wahed@pitt.eduwahed
Committee MemberMarsh, Gary M.gmarsh@pitt.edugmarsh
Committee MemberTang, Gonggot1@pitt.edugot1
Committee MemberCheng, Yuyucheng@pitt.eduyucheng
Date: August 2017
Date Type: Completion
Defense Date: 18 June 2017
Approval Date: 25 September 2017
Submission Date: 9 August 2017
Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
Number of Pages: 86
Institution: University of Pittsburgh
Schools and Programs: School of Public Health > Biostatistics
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Date Deposited: 25 Sep 2017 14:36
Last Modified: 01 Sep 2022 05:15


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