$\mathbb{N}$icola $\mathbb{B}$ranchini

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Nicola Branchini

Research Fellow in the Department of Statistics at the University of Warwick, working with Gareth Roberts under the ProbAI Hub

📄 Resume
Nicola Branchini
About

Hello! I am a Research Fellow in the Department of Statistics at the University of Warwick, working with Gareth Roberts under the ProbAI Hub. Sometimes I blog as well here.

Previously, I was a PhD student in Statistics in the School of Mathematics at the University of Edinburgh, advised by Víctor Elvira, and an ELLIS PhD student co-advised by Aki Vehtari at Aalto University.

My real interests are broad, spanning computational statistics and statistical/probabilistic machine learning, with a focus on methodology. For my PhD, I have been focussing on developing methodology in Monte Carlo.

A sample of some specific interests:

  • Importance sampling ∩ Markov chain Monte Carlo: IS is often viewed as a classical, somewhat “naive” method that struggles with complex problems such as high dimensions. Yet it remains central to applications ranging from Boltzmann generators and LLM training to estimating rare outputs of generative models. More advanced methods, such as Sequential Monte Carlo, are fundamentally based on IS. I remain interested in the mathematical properties of IS estimators: when they can work in high dimensions, which population- and sample-based metrics are appropriate, how they behave with infinite variance or heavy-tailed targets, and how combinations such as MCMC-IS can be understood. Ultimately, MC methods are used wherever an accurate answer matters, and understanding how much an answer can be trusted requires mathematics.
  • Monte Carlo ∩ generative models: What is the role of Monte Carlo methods in understanding the properties of generative models, like LLMs, diffusion models, etc.? For instance, we have been working on estimating probabilities of rare outputs in masked diffusion language models.
  • …and adjacent ideas: I like continuosly learning new concepts from neighbouring fields. There are so many interesting ideas still to explore!

Please do not hesitate to contact me for talking about research.

News
  • Pleased to announce that our paper on adaptive SNIS via MCMC was rejected (yes, you read it right) by NeurIPS 2026 with superficial feedback! Looking forward to submit to a journal.
  • Happy to share that I passed my PhD viva in June! Many thanks to my examiners Art Owen and Grégoire Clarté.
  • Happy to be invited for a talk at StaTalk 2026 in Torino.
  • Happy to give a contributed talk at the London Meeting on Computational Statistics at UCL.
  • Happy to give a contributed talk at MCQMC 2026 in Edinburgh.
  • Looking forward to attending the ProbAI workshop at the Isaac Newton Institute in Cambridge in March, as part of the Hub’s activities.
  • Recently joined the University of Warwick as a ProbAI research fellow, where I will work with Gareth Roberts.
  • Three new papers in 2026: How to approximate inference with subtractive mixture models (AISTATS 2026), On the bias of variational resampling (AISTATS 2026), and Multimarginal Flow Matching with Adversarially Learnt Interpolants (ICLR 2026). See more details on the publications page.
  • Our conference paper Towards Adaptive Self-Normalized Importance Samplers is accepted at the Statistical Signal Processing Workshop (SSP), 2025.✰
Reviewing

Journals

Statistics and Computing, Transactions on Machine Learning Research, Statistics and Probability Letters

Conferences & Workshops

AISTATS 2023, AABI (workshop) 2023, NeurIPS 2023, ICLR 2024, AISTATS 2024, NeurIPS workshop on Bayesian decision-making and uncertainty 2024, AISTATS 2025

Nice quotes
Basically, I'm not interested in doing research and I never have been. I'm interested in understanding, which is quite a different thing. And often to understand something you have to work it out yourself because no one else has done it
— David Blackwell
Getting numbers is easy; getting numbers you can trust is hard.
— Ron Kohavi, Diane Tang, Ysa Xu (from "Trustworthy Online Controlled Experiments")