Staff Directory

I’m excited to start this new journey with SIG! I’m passionate about developing interventions to improve the well-being of marginalized children and youth. I look forward to the learning opportunities at SIG.

Xinyu Zhang is a master’s student in Statistics at Columbia University, with bachelor’s degrees in Statistics and Accountancy from the University of Illinois Urbana-Champaign. Her research assistant work at Renmin University of China focuses on data governance and firms’ digital transformation, and her earlier work at Illinois examined environmental exposure and health outcomes. These projects have given her experience in data preparation, statistical analysis, and causal inference. "Through the AI4SGS mentored research program, I want to strengthen my research skills and better understand how statistical methods can help address practical problems," she said. "Working with Social Work researchers will also help me understand the community context behind the data. In WINGS+++, I am interested in contributing to pilot data analysis and exploring AI tools that help staff understand participants’ needs." She hopes to pursue a PhD in economics or a related field, with research interests in health economics and social policy.

Xinyi Wang is a master’s student in Statistics at Columbia University. Her research interests include machine learning, large language models, and reliable AI systems. She joined the AI4SGS mentored research program because she wanted to better understand how technical methods can be applied to real social problems. The collaboration between the School of Social Work and the Statistics Department gives her the opportunity to learn from both quantitative methods and domain expertise. She is especially interested in how AI systems can support research while remaining reliable, interpretable, and responsive to human needs. Through this experience, Xinyi hopes to strengthen her ability to define meaningful research questions, evaluate AI systems in real-world settings, and work across disciplines.

Wenze Li is an MA student in Statistics at Columbia University, with a prior background in insurance studies. He has a strong interest in applying statistical and data-driven methods to social research, especially for promoting health and well-being. His work draws on the HEAL study, using statistical methods to support evidence-based research and inform practical decision-making in health and social systems.

Dr. Susan Witte’s research focuses on the development and testing of prevention and treatment interventions targeting the co-occurrence of HIV/AIDS risk behaviors, substance abuse, and interpersonal violence among vulnerable populations.

University Professor Dr. Nabila El-Bassel is a top-cited intimate partner violence, HIV, and substance use researcher focused on marginalized communities.

Since she co-founded SIG in 1990 Dr. Nabila El-Bassel has used science to bring evidence-based solutions to social and health problems. In 2019, Dr. El-Bassel received Columbia University's highest academic honor when she was appointed to the rank of University Professor.

Menglei Zhang is a graduate student at Columbia University starting in Fall 2025. Her interests are the application of computational methods to real-world problems.  She says “I’m excited to be part of the AI4SGS Mentored Research Program because I’m interested in exploring how AI and statistical methods can be used to address real-world social challenges”. She is particularly interested in the opportunity to work on interdisciplinary research and learn how computational approaches can be connected with social work and community needs.

She hopes that this experience will help her to better understand the connection between academic research and real-world applications, including where the gap between academia and industry lies. At the same time, she hopes to explore her own interests and gain a better sense of the direction she would like to pursue in the future.

Maria Cedeno is the Director of Administration and Finance for SIG.

As a survivor of intimate partner violence myself, I am honored to work at SIG. The research conducted at SIG emphasizes the people and experiences that have been historically overlooked in the field of intervention development. I am excited to learn from an amazing team of thinkers who are pushing boundaries!

Dr. Lynn Murphy Michalopoulos has an extensive background in clinical social work and research related to trauma and HIV.

Dr. Gilbert's research focuses on developing and evaluating interventions that address gender-based violence, substance misuse and HIV among women.

Executive Assistant to Dr. Nabila El-Bassel

Dr. Wu's HIV prevention and intervention research emphasizes social justice and ameliorating health disparities by targeting “-isms.” 

Eleni Vlachos formerly directed the marketing and communications function for SIG.

Associate Professor Desmond Upton Patton’s research uses qualitative and computational data collection methods to examine the relationship between youth and gang violence and social media; how and why violence, grief, and identity are expressed on social media; and the real world impact these expressions have on well-being for low-income youth of color.

Dr. Goddard-Eckrich develops and implements programs and interventions to address health disparities affecting underserved populations.

Dr. Claudia Stoicescu’s research explores the impact of police enforcement activities on HIV risk, prevention and treatment outcomes among marginalized populations, including women who inject drugs and persons involved with the criminal justice system. Her research is rooted in participatory, community-based approaches and employs integrated knowledge translation to inform appropriate interventions and relevant policy decisions.  

At SIG, Dr. Stoicescu will examine the gendered impacts of policing on health HIV outcomes of people who use drugs with Drs. El-Bassel and Gilbert.

Chi (Charlie) Zhang is a master’s student in Statistics at Columbia University in the Advanced Machine Learning track. His academic training focuses on statistical learning and applied machine learning, with an emphasis on rigorous model evaluation and methodological reliability in real-world text and social science data. He is particularly interested in the use of large language models for qualitative research, including topic modeling and automated coding of text data. His prior work includes developing retrieval-augmented generation (RAG)–based systems for document analysis and conducting empirical evaluations of machine learning models under noisy data conditions.

As part of the AI4SGS program, Chi looks forward to contributing to the ENVIO research team by supporting rigorous comparisons between LLM-based coding and human annotation, with the goal of improving analytic reliability and research workflow efficiency in social science and public health research.

Cheryl is the Associate Director of the Criminal Justice Initiative: Supporting Children, Families, and Communities (CJI), where she works with teens who have an incarcerated parent, and the Senior Director of Education and Programs at Columbia University’s Center for Justice where her work is committed to reducing the nation’s reliance on incarceration, developing new  approaches to safety and justice, and participating in the national and global conversation around developing effective criminal justice policy.

Focus: Social determinants of health and mental health care, sleep, cardiovascular health disparities, and Latino immigrant health. Use quantitative and qualitative methods to examine how understudied aspects of the migration, socioeconomic, and psychosocial context contribute in unique ways to mental health, sleep, and cardiovascular health risk behaviors and outcomes.

Utilizing mixed method, network, and intervention approaches, Dr. Brooke West's research focuses on the social, economic, physical and policy factors underlying disparities in health among marginalized and criminalized populations. Her scholarship is situated at the intersection of social justice and health, centering primarily on the social determinants of substance use and HIV/STI, with newer work examining violence exposure and reproductive health.

Audrey Ward is the Associate Director of Operations for SIG.

Dr. Alissa Davis conducts research on linkage to and retention in HIV, sexually transmitted infections (STI), and substance use care among marginalized populations, including racial/ethnic and sexual minorities, people who inject drugs, and individuals involved with the criminal justice system.

Alisa He is an MA student in Statistics at Columbia University. She is interested in how statistical and AI methods can be used responsibly in health and social service settings. Her prior work spans information retrieval, Bayesian modeling, and large language model development. Through the AI4SGS program, she hopes to learn how rigorous analysis and human-centered AI can support the people delivering care rather than replace their judgment. She sees this experience as a foundation for a career building statistical and AI tools that are accurate, fair, and trustworthy in sensitive real-world settings.