Seth Axen 🪓

Quick intro 👋! I help scientists use ML in their research. My background is in structural biology, but I now mostly post about FOSS topics. I've worked on tools for manifolds and autodiff, but these days I mostly focus on tools for Bayesian analysis, e.g. ArviZ. In my free time, I powerlift.

Now that I'm job searching again, I've considered sticking this gem at the top of a resume just to see what happens.

Very cool paper

A FAQ is what to do in case of high Pareto-k's with PSIS-LOO or PSIS-LOGO. In case of hierarchical models we can integrate out group specific parameters before PSIS. We investigated reliability of some alternative integration methods with the eventual goal of automating this arxiv.org/abs/2609.05713

These PhD projects look like a ton of fun!

Bring 👏back 🦶blue books! 📘

Amortized Bayesian Workflow Chengkun LI, Aki Vehtari, Paul-Christian Bürkner et al. Action editor: Tom Rainforth https://openreview.net/forum?id=osV7adJlKD #mcmc #generative #amortized

ArviZ 1.0 is out! We have refactored it to be more modular, flexible & lightweight. For an overview of the changes, check the migration guide. python.arviz.org/en/stable/us...

"Other extensions of the factorial function do exist, but the gamma function is the most popular and useful. " did the gamma function herself/itself write this

Anyone aware of a collection of agent skills tailored towards FOSS workflows for package development and maintenance? Strongly considering writing my own.

If you have been using LOO-PIT, this is a must read for you! @herman-tesso.bsky.social has done excellent work with this paper! Thanks for @florencebockting.bsky.social and @aloctavodia.bsky.social for getting this to bayesplot and ArviZ. I'll notify when I have my casestudies updated with this

Over the break I was picking away at a personal project where brms is clearly the best tool to use, and hot damn, is brms nice!

Introduce yourself as what almost killed you: Hi there, I'm a hernia

I believe eigen fly. I believe eigen touch the sky.

Finally got around to trying out @typst.app, and I'm really surprised how easy the learning curve coming from TeX has been! I'm still not convinced it has all of the features I would want to replace TeX for papers, but it might replace my current TeX-in-MD derivation workflow.

Great new work from the labs of @jakhmack.bsky.social and @philipp.hertie.ai! The software Jaxley enables brain simulations which both imitate the processes in the brain in detail and can solve challenging cognitive tasks. Press release of @unituebingen.bsky.social: uni-tuebingen.de/en/universit...

We figured out flow matching over states that change dimension. With "Branching Flows", the model decides how big things must be! This works wherever flow matching works, with discrete, continuous, and manifold states. We think this will unlock some genuinely new capabilities.

Fisher meets Feynman! 🤝 We use score matching and a trick from quantum field theory to make a product-of-experts family both expressive and efficient for variational inference. To appear as a spotlight @ NeurIPS 2025. #NeurIPS2025 (link below)

MC Stan is here! Follow for the latest Stan news, and tag if you want us to repost your posts about new papers, packages, courses, etc. about Stan

From hackathon to release: sbi v0.25 is here! 🎉 What happens when dozens of SBI researchers and practitioners collaborate for a week? New inference methods, new documentation, lots of new embedding networks, a bridge to pyro and a bridge between flow matching and score-based methods 🤯 1/7 🧵

My paper with Loucas Pillaud-Vivien and Lawrence Saul, “Variational Inference for Uncertainty Quantification: An Analysis of Trade-offs”, has been accepted for publication in the Journal of Machine Learning Research. 📃 arxiv.org/abs/2403.13748 🧵 1/

Working from home and overhearing my 7-year-old trying to explain "countable infinity" to my partner using donuts.

Fun read of their amazing contributions to the SBI hackathon! 🥐 The SBI-Pyro bridge that @sethaxen.com built has a lot of potential I believe. I'll actually be presenting this work at @euroscipy.bsky.social this Wednesday - excited to share this with a broader audience. euroscipy.org/talks/KCYYTF/

All three books I've co-authored are freely available online for non-commercial use: - #Bayesian Data Analysis, 3rd ed (aka BDA3) at stat.columbia.edu/~gelman/book/ - #Regression and Other Stories at avehtari.github.io/ROS-Examples/ - Active Statistics at avehtari.github.io/ActiveStatis...

Pro-tip: don't be the poor sod that adds a daily cron trigger to a GitHub Actions workflow that often fails. Long after you've left the project, you will get *daily* failure notifications, and the only way out is to trick some other poor sod into editing the workflow. docs.github.com/en/actions/c...

For the Bayesians, it's the Monte Hall problem.