#  Researchers 

 



Researchers and Post-Doctoral Fellows are listed here. Other department members include, [**Faculty**](/faculty), [**Graduate Students**](/graduate-students) and [**Staff**](/staff).



 

 Postdoctoral Fellows Visiting Scholars  

## Postdoctoral Fellows

 

 

  [### Xueqing Liu

 ](/people/xueqing-liu)She/her/hers

Postdoctoral Fellow

 

 

 Research Interests: Mobile health, Causal inference, Statistical reinforcement learning 

 

 

      ![Xueqing Liu](/sites/g/files/omnuum10116/files/styles/hwp_4_5__690x865/public/2025-08/xueqingliu.png?itok=GYNI0_Qn) 

 

 

 

   [### Gabriel Arpino

 ](/people/gabriel-arpino)He/him/his

Postdoctoral Fellow

 

 

 Research Interests: Machine learning, O ptimization, H igh-dimensional statistics, A pplied probability 

 

 

      ![Gabriel Arpino](/sites/g/files/omnuum10116/files/styles/hwp_4_5__690x865/public/2025-09/Gabriel%20Arpino.png?itok=JeJjlxcl) 

 

 

 

   [### Yongkai Chen

 ](/people/yongkai-chen) <yongkaichen@fas.harvard.edu>He/Him/His 

Postdoctoral Fellow

 

 

 Research interests: Nonparametric and Bayesian methods, Machine learning, Bioinformatics 

 

 

      ![Yongkai Chen](/sites/g/files/omnuum10116/files/styles/hwp_4_5__690x865/public/statistics-2/files/yongkai.pic_.jpg?itok=GJOXTzZx) 

 

 

 

   [### Asim Gazi

 ](/people/asim-gazi) <agazi@seas.harvard.edu>(He/Him/His)

Postdoctoral Fellow

 

 

 Research Interests: Mobile Health Technology, Just-in-Time Adaptive Interventions, Reinforcement Learning, Uncertainty Quantification, Uncertainty-Informed Decision Making, Time Series Modeling 

 

 

      ![Asim Gazi Picture](/sites/g/files/omnuum10116/files/styles/hwp_4_5__690x865/public/statistics-2/files/gazia-resized-directory-9-8-2023.jpeg?itok=B-785R0A) 

 

 

 

   [### Bhanu Teja Gullapalli

 ](/people/bhanu-teja-gullapalli) <bgullapalli@seas.harvard.edu>He/Him/His

Postdoctoral Fellow

 

 

 Research Interests: Mobile Health Sensing, Substance use and addiction 

 

 

      ![Bhanu Teja, Gullapalli](/sites/g/files/omnuum10116/files/styles/hwp_4_5__690x865/public/2025-09/Bhanu_photo_cropped3.jpeg?itok=fa07XOOP) 

 

 

 

   [### Nicolas Leenaerts

 ](/people/nicolas-leenaerts) <nicolasleenaerts@fas.harvard.edu>Postdoctoral Fellow

 

 

 Research interests: Psychiatry, Addiction, Ecological Momentary Assessment, JITAIs, Machine Learning, Reinforcement Learning 

 

 

      ![Nicolas Leenaerts](/sites/g/files/omnuum10116/files/styles/hwp_4_5__690x865/public/2025-07/Nicolas_Leenaerts_Resized%20headshot%20PNG.png?itok=wytIKYbG) 

 

 

 

   [### Zhaoyang Shi

 ](/people/zhaoyang-shi-0) [zshi@fas.harvard.edu ](<mailto:zshi@fas.harvard.edu >)He/Him/His

Postdoctoral Fellow

 

 

 Research Interests: Network analysis, Geometric and topological statistics, Nonparametric and kernel methods 

 

 

      ![Zhaoyang Shi](/sites/g/files/omnuum10116/files/styles/hwp_4_5__690x865/public/statistics-2/files/zhaoyang_shi_headshot.png?itok=gFqsVX_n) 

 

 

 

   [### Ke Sun

 ](/people/ke-sun)He/Him/His

Postdoctoral Fellow

 

 

 Research Interests: Statistical Reinforcement Learning, Machine Learning 

 

 

      ![Ke Sun](/sites/g/files/omnuum10116/files/styles/hwp_4_5__690x865/public/statistics-2/files/ke_sun_photo.png?itok=5UsKZYCq) 

 

 

 

  

 

 

 

 



 

 

 

## Visiting Scholars 

 

 

  [### Hsin-Yu Lai

 ](/people/hsin-yu-lai)Associate

 

 

 Research Interests: Inference Reinforcement Learning Healthcare Signal Processing 

 

 

      ![Yu-Hsin Lai](/sites/g/files/omnuum10116/files/styles/hwp_4_5__690x865/public/statistics-2/files/hsin-yu-lai.png?itok=2iAgQotI) 

 

 

 

   [### Tianle Liu

 ](/people/tianle-liu) <tianleliu@fas.harvard.edu>He/him/his

Associate

 

 

 Research Interests: Machine learning, Probability theory, Causal inference 

 

 

      ![Tianle Liu](/sites/g/files/omnuum10116/files/styles/hwp_4_5__690x865/public/2025-08/Tianle%20Liu_updated.png?itok=hG5xZz8K) 

 

 

 

   [### Lester Mackey

 ](/people/lester-mackey)He/him/his

Associate 

 

 

 Research Interests: Statistical machine learning, scalable algorithms, high-dimensional statistics, approximate inference, probability, distribution compression, climate and weather forecasting, social good 

 

 

      ![Lester Mackey](/sites/g/files/omnuum10116/files/styles/hwp_4_5__690x865/public/2025-09/Lester%20Mackey-headshot-associate%20.png?itok=zTaTf1Zf) 

 

 

 

   [### Daniel Nevo

 ](/people/daniel-nevo)He / him / his

Faculty Visitor

 

 

 Research Interests: Causal inference, Time-to-event data, Econometric methods, Bio-medical applications. 

 

 

      ![Daniel Nevo](/sites/g/files/omnuum10116/files/styles/hwp_4_5__690x865/public/2025-08/Daniel%20Nevo_Resized_png.png?itok=kuV6Qj-T) 

 

 

 

   [### Ziping Xu

 ](/people/ziping-xu) <zipingxu@fas.harvard.edu>(He / Him / His)

Associate

 

 

 Research Interests: Statistical Reinforcement Learning, Mobile health 

 

 

      ![Ziping Xu Photo](/sites/g/files/omnuum10116/files/styles/hwp_4_5__690x865/public/statistics-2/files/xuziping.jpg?itok=9lJBhMik)