Postdoctoral Research in Statistical Modeling, Machine Learning, and Privacy-Aware Data Analysis

Current work in statistical modeling, machine learning, and applied data analysis.

I am a Postdoctoral Research Fellow at George Mason University. My recent work spans healthcare analytics, robust learning under distribution shift, large language models, transportation safety, and privacy-preserving statistical inference.

  • Healthcare analytics and classification under uncertainty
  • Robust learning, LLM uncertainty, and adaptive AI systems
  • Privacy-aware inference, stochastic processes, and rare-event modeling

Professional Experience

Current role

A focused snapshot of my current postdoctoral work.

Professional experience

  • Aug 2025-Present
    Postdoctoral Research Fellow

    George Mason University. Working on robust machine learning, uncertainty quantification, and privacy-aware modeling for healthcare and transportation datasets.

Publications

Selected papers and manuscripts

When a public version is available, the title links directly to the paper.

Under review · 2026

Learning History-Aware Paraphrase Robustness in LLMs under Epistemic Uncertainty from Dependent Logs

Fengnan Deng, Anand N. Vidyashankar

Current manuscript on robust LLM training under epistemic uncertainty and dependent conversational logs.

In process · 2026

Duplicates in Prior Authorization Data: Uncovering the Prevalence, Implications, and Strategies for Mitigating Privacy Risks

Joshua Sabiiti, Melissa Halm, Fengnan Deng, Anand N. Vidyashankar

Collaborative work on privacy risks and data quality issues in prior authorization records.

In process · 2025

Local Limit Theorem and Large Deviations for Branching Process with Immigration

Fengnan Deng, Anand N. Vidyashankar

Current manuscript on local limits, oscillation behavior, and large deviations across growth regimes.

In process · 2025

Private and Robust Inference for Hawkes Process Data and Integer-Valued Autoregression

Fengnan Deng, Anand N. Vidyashankar

Robust and privacy-aware inference for Hawkes process data with a link to integer-valued autoregression.

Research

Selected projects

A mix of current postdoctoral work and recent statistical research. Each project page gives a short overview, key methods, and currently available materials.

Skills

Technical toolkit

Methods and tools most relevant to applied quantitative, machine learning, and research roles.

Programming

Python R Matlab SAS SQL C++

Research areas

Applied Machine Learning Large Language Models Healthcare Analytics Predictive Modeling Privacy-Aware Data Analysis Large Deviations Hawkes Processes Branching Processes

Workflow and communication

Uncertainty Quantification Scientific Writing Reproducible Experiments Team Collaboration Technical Presentations Adaptability

Background

Education, teaching, talks, and service

Additional academic background and professional activity.

Education and recognition

  • George Mason University PhD in Statistical Science, Aug 2025
  • Rutgers University M.S. in Statistics, May 2019
  • Shandong University B.S. in Mathematics, May 2017
  • Washington Statistical Society Outstanding Graduate Student Award 2022

Teaching and service

  • Teaching Assistant Probability and Statistics for Engineers and Scientists, 2019-2022
  • Reviewer service Bernoulli; Statistical Analysis and Data Mining

Selected talks

  • R. Clifton Bailey Statistics Seminar Series, 2025 History-Aware Kullback-Leibler Accountant for Epistemic Uncertainty in Large Language Models
  • CFE and CMStatistics 2024 Sharp large deviations for branching process with immigration
  • ICORS 2024, WNAR 2024, JSM 2024 Talks on privacy, Hawkes processes, and robust estimation