BERD Co-Investigators

For a brief summary of each expert’s qualifications & background, or for their contact information, please see below.


Chi-Yang Chiu, PhD
Assistant Professor, Preventive Medicine
Dr. Chiu is interested in both methodological and applied work in the fields of statistical genetics, mixed effects models and nonparametric modeling. He also enjoys collaborative work with biomedical researchers on various topics. Dr. Chiu obtained his PhD in Statistics from the University of California, Santa Barbara and received post-doctoral training at the Eunice Kennedy Shriver National Institute of Child Health and Human Development. Dr. Chiu is also a guest researcher in Statistical Genetics Section at the National Human Genome Research Institute

Tamekia Jones, PhD
Associate Professor, Pediatrics & Preventive Medicine
Tamekia L. Jones, PhD, is an Associate Professor in the Department of Pediatrics with a secondary appointment in the Department of Preventive Medicine. Dr. Jones is a biostatistician for the Children’s Foundation Research Institute. In this role, she assists investigators with study design, sample size and power calculations, and statistical analyses. Prior to joining UTHSC, Dr. Jones served as a senior statistician for frontline Acute Lymphoblastic Leukemia clinical trials in the Children’s Oncology Group at the University of Florida. Her research interests include clinical trials, survival analysis, obesity, and health disparities.

Mehmet Kocak, PhD
Associate Professor of Biostatistics, Preventive Medicine
Mehmet earned his MSc degree in applied statistics from Michigan State University and a PhD in statistics from the University of Memphis. He has been a study biostatistician for numerous Phase-I and Phase-II clinical trials conducted by St. Jude Children’s Research Hospital from 2002-2011 and by Pediatric Brain Tumor Consortium (PBTC) from 2002-present, and for clinical and observational studies conducted by University of Tennessee Health Science Center (UTHSC) since 2011. His areas of research have been time-course gene expression data analysis, meta-analysis of p-values, Phase-I clinical trial design, Survival analysis, and categorical data analysis. He is an expert in the SAS programming language as well as SAS/Graph.

Śaunak Sen, PhD
Professor and Chief of Biostatistics, Preventive Medicine
Śaunak Sen, PhD, is Professor and Chief of Biostatistics in the Department of Preventive Medicine at the University of Tennessee Health Science Center. His specialties are statistical genetics and the analysis of high-dimensional data. He has contributed to statistical and computational methods for genetic analysis in model organism and admixed populations. He obtained his PhD from the University of Chicago; after postdoctoral stints at Stanford University and the Jackson Laboratory, he spent 12 years on the faculty at UCSF, before joining UTHSC in 2015. He has served on grant review panels for NIH and other agencies; he is an associate editor for the journal Genetics.

Fridtjof Thomas, PhD
Associate Professor of Biostatistics, Preventive Medicine
Dr. Thomas’ special research interests lie in statistical aspects of causality in the health sciences and the design of observational studies (also including secondary data analyses and chart reviews). Dr. Thomas is the co-investigator/biostatistician on several NIH funded studies. He is a member of the Biostatistics Collaborative Core at the Southeast Regional Center of the NHLBI-funded Women’s Health Initiative (WHI) study that has recruited over 160,000 women in over 40 clinical centers nationwide and is a member of the Design and Analysis Committee of the NIH-funded EARLY trials. He has served as grant reviewer for the Department of Defense’s Congressionally Directed Medical Research Program (CDMRP) and for the NIH Neurological, Aging and Musculoskeletal Epidemiology Study Section (NAME). He is Vice President of the Western Tennessee Chapter of the American Statistical Association (WTASA) and is Associate Editor of the Journal of Statistical Computation and Simulation (JSCS).

Elizabeth Tolley
Professor of Biostatistics, Preventive Medicine
Dr. Tolley holds a doctorate from Virginia Tech, Blacksburg, VA, and received post-doctoral training in building statistical models at North Carolina State University, Raleigh, NC. As a faculty member at UTHSC, she is course director of the two-semester graduate-level course in Biostatistics for the Health Sciences I and II and for the graduate-level course in Linear Regression Models offered in the Masters of Epidemiology degree program. She has mentored numerous graduate students at the masters and doctoral levels. Dr. Tolley has served as a biostatistician, co-investigator, and consultant on many NIH grants. She also provides biostatistical consulting and collaboration services for many basic science and clinical investigators as part of her assigned faculty duties. Throughout her career, Dr. Tolley has worked with clinical investigators to develop mechanistic or diagnostic models of disease outcomes and predictive models of such outcomes.

Jim Wan, PhD
Professor of Biostatistics, Preventive Medicine
Dr. Jim Y. Wan received his BS in Mathematics from the Chinese University of Hong Kong in 1981, & his PhD in Statistics from Yale University in 1987. He collaborates with faculty across the whole campus on statistical methods for clinical and epidemiologic data and health services research. These collaborations have resulted in more than 130 peered-reviewed articles and close to 200 abstracts presented in major national and international scientific conferences. His research interest has been devoted to the analysis of failure time data. Competing risks must be taken into account in the study of how risk factors affect a specific cause of failure. In the past he studied two generalized Cox regression models in the competing risks setting. Another research interest is the use of Poisson regression and logistic regression in epidemiologic studies. This has resulted in a publication on Poisson regression.


Tristan Hayes
BERD Consulting Manager, Preventive Medicine
Tristan Hayes is the Biostatistics, Epidemiology, and Research Design (BERD) consulting manager for iRISE at the University of Tennessee Health Science Center. He has a degree in economics from Middlebury College. Tristan enjoys connecting researchers with the tools and resources they need to succeed in their research. He has extensive experience in litigation and economic consulting and “likes to get his hands dirty with data in SAS”.


Trish Goedecke, MS
Staff Statistician, Preventive Medicine
Trish Goedecke, MS, is a staff statistician with the Department of Preventive Medicine at the University of Tennessee Health Science Center. She earned her MS in Actuarial Science from Central Washington University (CWU) and is studying toward a doctorate in Statistics at the University of Memphis (UM), focusing on Topic Modeling. She has conducted statistical and other data analyses with CWU, Milliman Health Consulting and the Institute for Intelligent Systems at UM, specializing in mixed linear regression modeling. As staff statistician, she is available for consulting on study design and statistical analyses.


Jiajing Wang, MS
Staff Statistician, Preventive Medicine
Jiajing Wang, MS, is a staff statistician in the Department of Preventive Medicine at the University of Tennessee Health Science Center. She received her MS in Statistics from The George Washington University. She was a volunteer in the Rehabilitation Medicine Department at the NIH and has experience working on data manipulation and applied statistical analysis. Her research areas of interest include Survival analysis, logistic regression and data mining.