Seminars and Invited Talks



Oct 26, 2018 Robert B. Gramacy, Ph.D.

Department of Statistics
Virginia Tech
Blacksburg, VA

Replication or Exploration? Sequential Design for Stochastic Simulation Experiments

We investigate the merits of replication, and provide methods that search for optimal designs (including replicates), in the context of noisy computer simulation experiments. We first show that replication offers the potential to be beneficial from both design and computational perspectives, in the context of Gaussian process surrogate modeling. We then develop a lookahead based sequential design scheme that can determine if a new run should be at an existing input location (i.e., replicate) or at a new one (explore). When paired with a newly developed heteroskedastic Gaussian process model, our dynamic design scheme facilitates learning of signal and noise relationships which can vary throughout the input space. We show that it does so efficiently, on both computational and statistical grounds. In addition to illustrative synthetic examples, we demonstrate performance on two challenging real-data simulation experiments, from inventory management and epidemiology.

One Capitol Square
Room 305

Nov 2, 2018 Antonio Canale, Ph.D.

Assistant Professor
Department of Statistical Science
University of Padua
Italy/Duke University
Durham, NC

Convex Mixture Regression for Quantitative Risk Assessment

There is wide interest in studying how the distribution of a continuous response changes with a predictor. We are motivated by environmental applications in which the predictor is the dose of an exposure and the response is a health outcome. A main focus in these studies is inference on dose levels associated with a given increase in risk relative to a baseline. Popular methods either dichotomize the continuous response or focus on modeling changes with the dose in the expectation of the outcome. Such choices may lead to information loss and provide inaccurate inference on dose-response relationships. We instead propose a Bayesian convex mixture regression model that allows the entire distribution of the health outcome to be unknown and changing with the dose. To balance flexibility and parsimony, we rely on a mixture model for the density at the extreme doses, and express the conditional density at each intermediate dose via a convex combination of these extremal densities. This representation generalizes classical dose-response models for quantitative outcomes, and provides a more parsimonious, but still powerful, formulation compared to nonparametric methods, thereby improving interpretability and efficiency in inference on risk functions. A Markov chain Monte Carlo algorithm for posterior inference is developed, and the benefits of our methods are outlined in simulations, along with a study on the impact of DDT exposure on gestational age.

One Capitol Square
Room 305

Nov 9, 2018 Huan (Helen) Wang, M.S.

Systems Analyst
Department of Biostatistics
Virginia Commonwealth University
Richmond, VA

Introduction to High Performance Computing Cluster

The Department of Biostatistics cluster leverages high performance resources needed to accommodate the competitive research requirements in biostatistical research. It has grown in response to VCU’s strategic plan and offers a centralized resource for high-performance computing (HPC) hardware and software support in an interdisciplinary environment. The facility is located at the University Computer Center. It includes 5 rack shelves with over 50 cutting edge nodes, over 1000 CPU cores and 350TB centralized storage with a parallel file system and InfiniBand network connection.

Our faculty and students are using it for high memory intensive and CPU intensive computations, leveraging software including R3.4 and SAS9.4, with Redhat Linux 7.5 installed as OS.

In the seminar, we will cover “when” and “why” the cluster should be used, with hands on practice for the new users to have a peek of the basic Linux warmup and cluster functions.

Please contact Helen if you plan to attend the seminar. You will need to have a server account in order to use it.

One Capitol Square
Room 305

Nov 16, 2018 Nitai Mukhopadhyay, Ph.D. & Viviana Alejandra Rodriguez

Department of Biostatistics
Virginia Commonwealth University
Richmond, VA

One Capitol Square
Room 305

Nov 19, 2018 Dipak Dey, Ph.D.

Distinguished Professor
Department of Statistics
University of Connecticut
Storrs, CT

One Capitol Square
Room 305

Nov 30, 2018 Preetam Ghosh, Ph.D.

Associate Professor
Department of Computer Science
Virginia Commonwealth University
Richmond, VA

One Capitol Square
Room 305

Previous Seminars

Oct 5, 2018 Levi Waldron. Ph.D.
Sep 28, 2018 John Muschelli, Ph.D.
Sep 21, 2018 Robert T. Krafty, Ph.D.
Sep 14, 2018 CANCELLED: Suprateek Kundu, Ph.D.
Aug 31, 2018 Student Research Symposium Presentations – Day 2
Aug 24, 2018 Student Research Symposium Presentations – Day 1
Jul 31, 2018 Hangcheng Liu
Jul 2, 2018 Amanda E. Gentry
May 4, 2018 Le Kang
Apr 27, 2018 Haitao Chu, M.D., Ph.D.
Apr 13, 2018 Victor H. Lachos Davila, Ph.D.
Mar 9, 2018 Yaping Liu, Ph.D.
Mar 2, 2018 Tin C. Nguyen, Ph.D.
Feb 23, 2018 Ekaterina Smirnova, Ph.D.
Feb 19, 2018 RESCHEDULED: Hongjian Zhu, Ph.D.
Feb 9, 2018 Chong Wu, Ph.D.
Feb 7, 2018 RESCHEDULED: Kingston Kang
Feb 2, 2018 Zhixiang Lin, Ph.D.
Jan 26, 2018 Leroy R. Thacker, II, Ph.D.
Dec 1, 2017 CANCELLED: Terrance D. Savitsky, Ph.D.
Nov 17, 2017 Nathan Sheffield, Ph.D.
Nov 3, 2017 Chongzhi Zang, Ph.D.
Oct 20, 2017 Huan (Helen) Wang, M.S.
Oct 13, 2017 Hua Liang, Ph.D.
Oct 6, 2017 Jianwen Cai, Ph.D.
Sep 29, 2017 CANCELLED: Emily Sheldon-Waniga, Ph.D.
Sep 22, 2017 Yanning Liu, Ph.D.
Sep 8, 2017 Tingting Zhang, Ph.D.
Aug 18, 2017 Student Research Symposium
Jun 19, 2017 Rebecca R. Lehman
Apr 28, 2017 Singdhansu Chatterjee, Ph.D.
Apr 14, 2017 Lukasz A. Kurgan, Ph.D.
Apr 11, 2017 Bhanu M. Evani, M.S.
Apr 7, 2017 Wenbin Lu, Ph.D.
Mar 31, 2017 Sujit K. Ghosh, Ph.D.
Mar 24, 2017 Stacia M. DeSantis, Ph.D.
Mar 10, 2017 Casey S. Greene, Ph.D.
Mar 3, 2017 POSTPONED: Tingting Zhang, Ph.D.
Feb 24, 2017 Montserrat Fuentes, Ph.D.
Feb 17, 2017 Samiran Sinha, Ph.D.
Feb 10, 2017 Xin (Cynthia) Tong, Ph.D.
Jan 27, 2017 Codruta Chiuzan, Ph.D.
Dec 2, 2016 Chao Du, Ph.D.
Nov 28, 2016 Zirui Gu
Nov 18, 2016 Hongkun Wang, Ph.D.
Nov 16, 2016 Kyle L. Ferber
Nov 11, 2016 Yanxun Xu, Ph.D.
Nov 10, 2016 Emily V. Dressler, Ph.D.
Nov 4, 2016 Mikhail Dozmorov, Ph.D.
Nov 3, 2016 Arindam RoyChoudhury, Ph.D.
Oct 28, 2016 Aaron Quinlan, Ph.D.
Oct 21, 2016 Bruce Swihart, Ph.D.
Oct 14, 2016 Bo Cai, Ph.D.
Oct 7, 2016 Helen Wang, M.S.
Sep 23, 2016 Cheng Ly, Ph.D.
Sep 16, 2016 Xiaowei Wu, Ph.D.
Sep 9, 2016 Brian J. Reich, Ph.D.
Aug 25, 2016 Vanda Inacio, Ph.D.
Aug 22, 2016 Hui Wang
Aug 18, 2016 Student Research Symposium
Jul 29, 2016 Kabita Joshi, MPH, M.S.
Jul 22, 2016 Edmund R. Glass
May 6, 2016 Jianlin Cheng, Ph.D.
May 4, 2016 Jenna N. Czarnota
Apr 29, 2016 Eric Vance, Ph.D.
Apr 28, 2016 Lauren P. Grant
Apr 27, 2016 Aobo Wang
Apr 26, 2016 Qing Zhou
Apr 22, 2016 Jenise L. Swall, Ph.D.
Apr 15, 2016 Jay Mandrekar, Ph.D.
Apr 8, 2016 Tom Arodz, Ph.D.
Apr 1, 2016 Jacob Wegelin, Ph.D.
Mar 25, 2016 Frank W. Rockhold, Ph.D.
Feb 12, 2016 Linda Corey, Ph.D.
Jan 29, 2016 Mikhail Dozmorov, Ph.D.
Dec 14, 2015 Seminar Schedule
Dec 4, 2015 Timothy York, Ph.D.
Dec 2, 2015 Uma Siangphoe
Nov 20, 2015 Tamas S. Gal, Ph.D.
Nov 13, 2015 Dongjun Chung, Ph.D.
Nov 9, 2015 Andrey Afanasyev
Nov 5, 2015 Frank Harrell, Ph.D.
Oct 28, 2015 Helen Wang, M.S.
Oct 23, 2015 Andrey Rzhetsky, Ph.D.
Oct 9, 2015 Dong-Yun Kim, Ph.D.
Oct 2, 2015 CANCELLED: Helen Wang, M.S.
Sep 18, 2015 Rui Feng, Ph.D.
Aug 21, 2015 Student Research Symposium
Jul 22, 2015 Mateusz Makowski
May 27, 2015 Shanshan Chen, Ph.D.
Apr 24, 2015 Hadiza I. Galadima
Apr 17, 2015 Alicia Y. Toledano, Sc.D.
Apr 10, 2015 CANCELLED: Gregory Buck, Ph.D.
Apr 3, 2015 Julian Rosenman, Ph.D., M.D.
Mar 27, 2015 Dipankar Bandyopadhyay, Ph.D.
Mar 20, 2015 Bridget Thomson-McInnes, Ph.D.
Mar 13, 2015 Chi Song, Ph.D.
Mar 6, 2015 Guofen Yan, Ph.D.
Feb 27, 2015 Michael R. Kosorok, Ph.D.
Feb 13, 2015 Minsun Song, Ph.D.
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