Predoctoral Fellows (2020-2021)
Jemar Bather
Academic Advisor: Paige Williams
Jemar is a third year PhD student in the Department of Biostatistics. Jemar’s current research interest is developing a more efficient and unbiased statistical methods for addressing critical questions in evaluating adverse birth outcomes in mothers with HIV. He is currently working on a project to assess the relationship between the empirical power of the inverse probability weighted GEE multiple informant model and the correlation between binary exposures when data is informatively missing. Jemar has conducted simulation studies and a thorough literature review, and will present the results along with his next project at his oral examination in March 2021.
Christina Fennell
Academic Advisor: Dr. Roger Shapiro
Christina is a second year PhD student in the Department of Epidemiology. Christina’s current research interest focuses on exploring barriers to accessing HIV care among marginalized populations. Her current research focuses on evaluating the impact of a recent policy expansion in Botswana, where non-citizens have access to free HIV treatment, among pregnant women. The project seeks to determine the impact of this policy expansion on uptake of government ART among non-citizen, pregnant women and on adverse birth outcomes. Christina is currently developing an analysis plan for this project which will include a descriptive analysis, an interrupted time series analysis, and an exploration of potential risk factors of adverse birth outcomes comparing citizen vs. non-citizen pregnant women. Christina also completed a project that sought to determine the impact of vaginal discharge syndrome and antibiotic use on adverse birth outcomes in Botswana. The project also explored if these associations varied by HIV status.
Linda Harrison
Academic Advisor: Rui Wang
Linda is a fourth year PhD student in the Department of Biostatistics. Linda’s research interests are power calculations for infectious disease clinical trials. Her current research looks at how stepped wedge cluster randomized trials (SW-CRTs), in which an intervention is rolled out sequentially to clusters of individuals, are ideal for pragmatic evaluation of infectious disease control. Existing methods for power calculation when designing a SW-CRT assume the cluster sizes are equal, which may lead to an underpowered study. Linda’s first paper proposes a method to calculate the minimum, maximum and average power of a SW-CRT with variable cluster sizes. Her second planned manuscript addresses power calculation for SW-CRTs when outcomes are binary. In clinical trials there are often missing outcome data. Standard approaches inflate the sample size as if outcome data are missing completely at random and a complete-case analysis will be conducted. Linda’s third paper addresses power calculation in clinical trials when outcome data are missing at random given fully observed covariates.
Jonathan Larson
Academic Advisor: Jukka-Pekka Onnela
Jonathan is a fifth year PhD student in the Department of Biostatistics. His research interests are statistical methods for network data. Jonathan’s first project proposes an affiliation network model of HIV transmission in men who have sex with men and evaluates an estimator of risk based on that model. His second project investigates what we can infer about the minimum spanning tree (MST) of a population graph based on the MST of a sample. And Jonathan’s third project compares different methods of estimating the parameters of the duplication-mutation-complementation (DMC) model of network evolution.
Lara Maleyeff
Academic Advisor: Dr. Rui Wang
Lara is a second year PhD student in the Department of Biostatistics. Her research interest is treatment effect heterogeneity in stepped wedge cluster randomized trials. Lara is currently working on her first paper which explores new modelling and testing frameworks for treatment effect heterogeneity in stepped wedge cluster randomized trials. These trials involve unidirectional cross-over to treatment, with time to cross-over randomized. Existing methodology to account for unknown patterns of exposure time heterogeneity have poor statistical properties. This work proposes a new model and testing framework. This work was submitted in an F31 grant last fall and for the Thomas C. Chalmers Student Scholarship for the Society of Clinical Trials 2021 conference.
Octavious Talbot
Academic Advisor: Jukka-Pekka Onnela
Octavious is a fifth year PhD student in the Department of Biostatistics. His research interests are around detecting homophily within network structures, and determining what factors influences relationship building in a social network. In his paper 1, he created a visual tool that can be used in exploratory data analysis to inspect for homophily in a network. In his paper 2, he is interested in using this tool but also doing further analytical inspection to determine what factors influence relationships being formed in an HIV network. In the network, genetic sequencing is done to infer connections.
Maxwell Wang
Mentor(s): Drs Molin Wang & Rui Wang
Max is a first year PhD student in the Department of Biostatistics. His research interest at this time is modeling of infectious disease transmission and the evaluation of public health interventions. His main focus at this time is on his coursework.
Stephanie Wu
Mentor(s): Drs. Bethany Hedt-Gauthier and Michael Hughes
Stephanie is a second year PhD student in the Department of Biostatistics. She has recently passed the department’s written qualifying exam. Her research interests center on outcome-dependent sampling for correlated binary outcomes, and survey sampling methodology for acquired HIV drug resistance. Stephanie is currently working on a project that looks at outcomedependent sampling for correlated binary outcomes to develop an efficient case-control study design nested within the PHOENIx trial, which is a cluster-randomized prevention trial comparing the efficacy of delamanid to isoniazid for prevention of active tuberculosis among high-risk household contacts of adults with multidrug-resistant tuberculosis. Research is currently ongoing and involves a numerical analysis and simulation study of possible study designs. Stephanie is also working on a project that aims to develop the statistical methods and tools for the WHO’s protocol on laboratory-based surveys of acquired HIV drug resistance using remnant viral load specimens. Acquired drug resistance to dolutegravir-based antiretroviral therapy is a particular focus of the survey, as is the usage of expanded availability of laboratory data in countries. The protocol has been copy-edited and is currently undergoing layout revisions.
Daniel Xu
Mentor(s): Dr. Michael Hughes
Daniel is a first year PhD student in the Department of Biostatistics. Daniel is interested in conducting research that ties together EHR data and clinical trials, and will begin work on an independent study project with Dr. Tianxi Cai this semester.
Postdoctoral Fellows (2020-2021)
Meredith Regan
Mentor(s): Dr. Christopher Sudfeld
Dr. Regan’s research focuses on the intersection of HIV and mental health in resource-limited settings, with the aim of informing interventions and policy. Specifically, she is interested in the ways in which mental health and social determinants of health affect adherence and access to HIV care. She is currently writing up a study based on data from the Familia Salama cluster randomized trial in Dar-es-Salaam, Tanzania. Dr. Regan’s analysis evaluates the impact of a community health worker intervention on frequency and timing of ANC visits and looks at various potential effect modifiers including HIV diagnosis. Having an ANC visit in the first trimester is particularly important for women living with HIV so that they can access prevention of mother-to-child HIV transmission services and initiate antiretroviral treatment if they are not already receiving it. Dr. Regan is also analyzing data from the Trial of Vitamin 5 (ToV5) trial, a cohort of pregnant women living with HIV. She is looking at the association between depression at baseline and birth outcomes, child health outcomes, and early childhood development outcomes. She is also interested in exploring the role of timing of ART initiation as about half the women in the cohort initiated ART at the beginning of the study. Finally, Dr. Regan is very interested in exploring questions around racial, geographic, and socioeconomic disparities in HIV outcomes in the US. She is particularly interested in how COVID-19 has affected access to HIV treatment, and has been doing background reading on this topic in order to formulate a research question and analysis plan.
Predoctoral Fellows (2018-2019)
Jemar Bather
Academic Advisor: Marcello Pagano
Jemar is a first year PhD student in the Department of Biostatistics. His current focus is completing his coursework.
Linda Harrison
Academic advisor: Marcello Pagano
Linda is a second year PhD student in the Department of Biostatistics. Her research with Dr. Rui Wang focuses on methods for sample size calculation in stepped wedge cluster randomized trials with variable cluster sizes.
Lee Kennedy-Shaffer
Academic advisor: Michael D. Hughes
Lee is a third-year PhD student in the Department of Biostatistics. His primary research focuses on methods for sample size estimation for cluster randomized trials (CRTs). In particular, he has focused on sample size estimation for stratified CRTs with binary outcomes in infectious disease settings and in what situations stratification can lead to reductions in sample size that have practical relevance to trial design. Included in this research is a deeper understanding of the role of the intracluster correlation coefficient (ICC) for binary outcomes and how the ICC is affected by stratification. Additional research, conducted with Professors Victor De Gruttola and Marc Lipsitch, focuses on methods for vaccine evaluation using novel trial designs and causal inference principles and methods.
Jonathan Larson
Academic Advisor: Jukka-Pekka Onnela
Jonathan is a third-year PhD student in the Department of Biostatistics. His research focuses on random graphs, particularly in the form of HIV transmission networks. Currently, he is developing a model of HIV transmission in men who have sex with men (MSM) based on information about where MSM meet sex partners. This model leads to a natural estimator of risk of infection. Jonathan is also interested in methods for sampling network data as well as methods for predicting characteristics of missing portions of networks.
Gabriel Loewinger
Academic advisor: Michael Hughes
Gabe is a second year PhD student in the Department of Biostatistics. His current focus is completing his coursework.
Mary Kate (MK) Quinn
Academic Advisor: Christopher Sudfeld
MK is a third-year PhD student in the Global Health and Population Department in Population Health Sciences. Her current research is focused on the mechanisms through which different micronutrient exposures affect pregnancy outcomes among women in Tanzania and Ghana. She is also investigating how the timing of ARV initiation during pregnancy affect fetal loss and birth outcomes among women in Tanzania living with HIV.
Dustin Rabideau
Academic Advisor: Rui Wang
Dustin is a third-year PhD student in the Department of Biostatistics. His research interests are broad but currently focus on robust methods for correlated data. Specifically, he is working on permutation methods (i.e. randomization inference) for cluster randomized trials. This general approach provides valid inference even with a small number of clusters, correlated clusters, and when the correlation structure is misspecified. Dustin has also worked with Dr. Judith Lok on inverse probability of censoring weighting when data are missing not at random.
Jaffer Zaidi
Academic advisor: Tyler VanderWeele
Jaffer is a fifth year PhD student in the Department of Biostatistics. Jaffer has worked on extending the sufficient cause model from binary outcomes to ordinal and categorical outcomes. This work is useful in understanding which HIV resistance mutations jointly make a particular drug ineffective. He has also worked on mediation, and is currently developing methods for mediation analyses that are more easier to interpret than existing methods and do not make assumptions beyond those licensed through experimental design. Jaffer worked previously in South Africa as an HIV epidemiologist.
Postdoctoral Fellows (2017-2018)
Elysia Larson
Elysia is a postdoctoral fellow in the Biostatistics department. She works at the intersection of communities and the health system, to measure how patient preferences and facility quality can and do interact to produce better quality of care and better health. Dr. Larson has been the PI, project manager, or statistician for multiple cluster-randomized evaluations of interventions that aim to improve quality of care and health for pregnant women and children living in regions with high HIV-prevalence.