The work in this year mainly involve two projects. First, for regression methods for bivariate failure time data, we have developed a statistical model and evaluated its performance through simulation studies. Also, the proposed methods have been applied to the WHI hormone therapy trials. Second, we proposed a improved family history score for risk prediction of breast cancer. This project was motivated by the Sister Study, where all participants have at least one sister with breast cancer. With traditional approach of considering family history as a yes/no variable, there is no ability to distinguish the risks of a women with 1 sister out of 10 with breast cancer versus a women with 3 sister out of 3 with breast cancer. The proposed family history score takes number of diseased sister, total number of sisters and ages of sisters into account. In our simulation and data analysis, the proposed family history score showed powerful predictiveness for breast cancer risk.

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U.S. National Inst of Environ Hlth Scis
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Carroll, Rachel; Lawson, Andrew B; Zhao, Shanshan (2018) Temporally dependent accelerated failure time model for capturing the impact of events that alter survival in disease mapping. Biostatistics :
Prentice, Ross L; Zhao, Shanshan (2018) Nonparametric estimation of the multivariate survivor function: the multivariate Kaplan-Meier estimator. Lifetime Data Anal 24:3-27
Carroll, Rachel; Lawson, Andrew B; Jackson, Chandra L et al. (2017) Assessment of spatial variation in breast cancer-specific mortality using Louisiana SEER data. Soc Sci Med 193:1-7
Zhao, Shanshan; Zheng, Yingye; Prentice, Ross L et al. (2015) Two-stage biomarker panel study and estimation allowing early termination for futility. Biostatistics 16:799-812
Nelson, Jennifer C; Cook, Andrea J; Yu, Onchee et al. (2015) Methods for observational post-licensure medical product safety surveillance. Stat Methods Med Res 24:177-93
Zhao, Shanshan; Prentice, Ross L (2015) Rejoinder to ""On the Misuse of Taylor Expansion"". Biometrics 71:1195