Statistics Seminar - 04/27/23

Apr 27 3:30 pm

Dr. Yichuan Zhao, Professor of Statistics, Department of Mathematics and Statistics, Georgia State University; Fellow of ASA


Statistics Seminar Series (Hybrid)


Novel Empirical Likelihood Inference for the Mean Difference with Right-Censored Data

Physical Location

Allen 17

Digital Location


This paper focuses on comparing two means and finding a confidence interval for the difference of two means with right-censored data using the empirical likelihood method combined with the i.i.d. random functions representation. Some early researchers proposed empirical likelihood-based confidence intervals for the mean difference based on right-censored data using the synthetic data approach. However, their empirical log-likelihood ratio statistic has a scaled chi-squared distribution. To avoid the estimation of the scale parameter in constructing confidence intervals, we propose an empirical likelihood method based on the i.i.d. representation of Kaplan–Meier weights involved in the empirical likelihood ratio. We obtain the standard chi-squared distribution. We also apply the adjusted empirical likelihood to improve coverage accuracy for small samples. We investigate a new empirical likelihood method, the mean empirical likelihood, within the framework of our study. Via extensive simulations, the proposed empirical likelihood confidence interval has better coverage accuracy than those from existing methods. Finally, our findings are illustrated with a real data set.



Dr. Yichuan Zhao is a Full Professor of Statistics, at Georgia State University, Atlanta. He has a joint appointment as an Associate Member of the Neuroscience Institute, and he is also an affiliated faculty member of the School of Public Health at Georgia State University. Dr. Zhao has a B.S. and an M.S. in Mathematics from Peking University, and an M.S. in Stochastics and Operations Research from Utrecht University. He received his Ph.D. in Statistics from the Department of Statistics at Florida State University in 2002 under the direction of Professor Ian McKeague. His current research interest focuses on survival analysis, empirical likelihood method, nonparametric statistics, statistical analysis of ROC curves, high-dimensional data analysis, bioinformatics, Monte Carlo methods, and statistical modeling of fuzzy systems. He has published 100 research articles in the Statistics and Biostatistics research fields. Dr. Zhao has organized the Workshop Series on Biostatistics and Bioinformatics since its initiation in 2012. The ICSA Springer Book from the workshop can be found through the New Frontiers of Biostatistics and Bioinformatics. He also organized the 25th ICSA Applied Statistics Symposium in Atlanta as chair of the organizing committee and program committee to great success. The ICSA Springer Book from the Symposium reflects new challenges in the contemporary data era; see the book: New Advances in Statistics and Data Science for details. A Springer Book reflects statistical modeling in biomedical research; see the book: Statistical Modeling in Biomedical Research. A Springer Book reflects advanced statistical methods for health research; see the book: Modern Statistical Methods for Health Research. He served on program committees of numerous statistical conferences and is currently serving on the editorial board, for several statistical journals including the Electronic Journal of Statistics, Journal of Nonparametric Statistics, and Journal of Applied Statistics. Dr. Zhao is a Fellow of the American Statistical Association and an elected member of the International Statistical Institute.