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Associate Member, St. Jude Faculty
Biostatistics
Xiaoping Xiong, PhD
Biostatistics
MS 768, Room R2033
St. Jude Children's Research Hospital
262 Danny Thomas Place
Memphis, TN 38105-3678
Email: xiaoping.xiong@stjude.org
Phone: (901) 595-2102
FAX: (910) 595-4585
BS - Southwestern Jiaotong University, Chengdu, Sichuan, China (Mathematics) (1982)
MS - Purdue University, West LaFayette, Indiana, USA (Statistics) (1988)
PhD - Purdue University, West LaFayette, Indiana, USA (Statistics) (1991)
My collaborative works are currently for clinical and biomedical studies from radiation oncology, diagnostic imaging, behavior medicine, and virology.
My interests in statistical research are on sequential analysis and stochastic modeling of biomedical processes. In sequential analysis, I am now focused on developing sequential methods for design and evaluation of clinical trials based on the sequential conditional probability ratio test (SCPRT). The ethical consideration and availability of subjects are major concerns in statistical design of clinical trials. Sequential procedures improve the efficiency of clinical trials by early detecting the validity or futility of promising new treatment as early as possible, which balance well the scientific merit with the ethical issue in clinical trials. Sequential designs were not always chosen by clinical investigators because some properties of sequential designs were not desirable in this application. The SCPRT procedure met the challenge by removing these undesirable properties and from the scientific point of view provides a sound reason to stop a clinical trial early: if the trial were not stopped as it should, then to add more data and continue the trial until the planned end would not change the conclusion. A sequential clinical trial by SCPRT is designed not only with given significance level and power, but also with a given probability of discordance which controls discrepancy in possible conclusions at different stages. I proposed this sequential design SCPRT in 1993 (Technical Report #93-15, Dept of Statistics, Purdue University) based on my Ph.D. thesis (Purdue University, 1991), and some of the results were published in 1995 (JASA). In recent years, I have developed SCPRT methods for a standardized test statistic on information time interval [0,1], and the methods are applicable to most clinical trials for which the test statistic herein can be approximated by a Brownian motion. I have developed SCPRT methods for monitoring clinical trials against historical controls, in which the data in a current trial are sequentially collected and compared with all data in a previous study. I have developed computer programs for implementing SCPRT methods for design and evaluation of sequential tests. A program for SCPRT on information time can be downloaded by clicking [download computer program SCPRTinfWin]. A program for SCPRT for binary data can be downloaded by clicking [download computer program SCPRTbn]. For my research on stochastic modeling for solving biomedical problems, I have recently published a paper on the estimation and testing of mutation rates, in which I proposed a stochastic model grounded with more realistic assumptions. This model explains the larger than expected variation in the estimation of mutation rates, which is a phenomenon that was observed by and has puzzled biologists for a long time. Based on this model, I proposed statistical methods for estimating and testing the mutation rates of cells and microbes with efficiency and accuracy.
Xiong X, Boyett J, Webster R, Stech J. A stochastic model for estimation of mutation rates in multiple-replication proliferation processes. Journal of Mathematical Biology, E-publication: October 2008. Web link
Merchant TE, Li C, Xiong X, LE Kun, Boop FA, Sanford RA. Conformal Radiation Therapy for Pediatric Ependymoma, Lancet Oncology 10(3):258-66, 2009.
Hoffer FA, Daw NC, Xiong X, Anghelescu D, Krasin M, Yan X, Davidoff A, Furman WL, Rodriguez-Galindo C, Spunt SL. A phase I/pilot study of radiofrequency ablation for the treatment of recurrent pediatric solid tumors, Cancer 115(6):1328-37, 2009.
Xiong X, Tan M, and Boyett J. A sequential procedure for monitoring clinical trials against historical controls. Statistics in Medicine (in press); published online in Wiley InterScience July, 2006. Web link [Associated Software]
Xiong X, Tan M, and Boyett J. SCPRT: A sequential procedure that gives another reason to stop clinical trials early. Advance in Statistical Methods for Health Sciences (Series in Statistics for Industry and Technology, Birkhauser:Boston): 419-434, 2006. Web link [Associated Software]
Tan WY, Zhang P, Xiong X, Flynn P. Assessment of treatment effects on HIV pathogenesis under treatment by state space models. Advance in Statistical Methods for Health Sciences (Series in Statistics for Industry and Technology, Birkhauser Boston): 305-322, 2006.
Fang HB, Tian G, Xiong X, and Tan M. A multivariate random-effects model with restricted parameters: applications to assessing radiation therapy for brain tumor. Statistics in Medicine 25:1948-1959, 2006.
Krasin MJ, Xiong X, Reddick WE, Ogg RJ, Hoffer FA, McCarville B, Kaste SC, Spunt SL, Navid F, Davidoff AM, Zhang L, Kun LE, Merchant TE. A model for quantitative changes in the magnetic resonance parameters of muscle in children after therapeutic irradiation. Magnetic Resonance Imaging 24: 1319-1324, 2006.
Merchant TE, Kiehna EN, Li C, Xiong X, Mulhern RK. Radiation dosimetry predicts IQ after conformal radiation therapy in pediatric patients with localized ependymoma. Int J Radiat Oncol Biol Phys 63(5):1546-54, 2005.
Mulhern RK, Khan RB, Kaplan S, Helton S, Christensen R, Bonner M, Brown R, Xiong X, Wu S, Gururangan S, Reddick WE. Short-term efficacy of methylphenidate: a randomized, double-blind, placebo-controlled trial among survivors of childhood cancer. Journal of Clinical Oncology 22(23):4743-51, 2004.
Xiong X, Yao WX, Tan M, and Yue GH. A Stochastic Model for Assessing Synchronization of Spike Trains in a Population of Motor Neurons. Methodology and Computing in Applied Probability 5: 355-367, 2003. Web link
Xiong X, Tan M and Boyett J. Sequential conditional probability ratio tests for normalized test statistic on information time. Biometrics 59(3):624-631, 2003. Web link
Steen RG, Hankins G, Xiong X, Wang WC, Beil K, Langston JW, Helton KJ, Prospective brain imaging evaluation of children with sickle cell trait: initial observations. Radiology 228:208-215, July 2003.
Xiong X, Tan M, Kutner MH. Computational Methods for Evaluating Sequential Tests and Post-test Estimations via Sufficiency Principle. Statistica Sinica 12(4):1027-1041, 2002.
Merchant T, Goloubeva O, Pritchard D, Gaber MW, Xiong X, Danish RK, Lustig RH. Radiation Dose-volume Effects on Growth Hormone Secretion. International Journal of Radiation Oncology Biology Physics 52(5):1264-70, 2002.
Xiong X and Tan M. Evaluating sequential tests for a class of stochastic processes. Computing Science and Statistics 33:30-34, 2001.
Tan M, Tian G, Xiong X. Explicit Bayesian solution for incomplete pre-post test problems using inverse Bayes Formulae. Communication in Statistics, Theorems and Methods 30(6):1111-1129, 2001.
Liu A, Boyett J, Xiong X. Sample size calculation for planning group sequential longitudinal trials. Statistics in Medicine 19:205-220, 2000.
Liu A, Tan M, Boyett J, Xiong X. Testing secondary hypothesis following sequential clinical trials. Biometrics 56:640-644, 2000.
Stech J, Xiong X, Scholtissek C, Webster R. Independence of evolutionary and mutation rates after transmission of avian influenza viruses to swine. Journal of Virology 73(3):1878-84, 1999.
Tan M, Xiong X, Kutner MH. Clinical trial designs based on sequential conditional probability ratio tests and reverse stochastic curtailing. Biometrics 54:682-695,1998.
Xiong X. Absorption probability distributions of random paths from finite populations. Sequential Analysis 15(1):1-19, 1996.
Tan M, Xiong X. Continuous and group sequential conditional probability ratio tests for phase II clinical trials. Statistics in Medicine 15:2037-2051,1996
Xiong X. A class of sequential conditional probability ratio tests. Journal of American Statistical Association 90(432):1463-1473, 1995.
Xiong, X. Principle of generalized conditional PLR sequential test and its applications. Technical Report 93-15, Department of Statistics, Purdue University, West Lafayette, Indiana, 1993.
Xiong, X. Absorption probability distributions of random paths from finite populations. Technical Report #92-41C, Department of Statistics, Purdue University, West Lafayette, Indiana, 1992.
Last update: July 2011
