David Hodgson
dchodge.bsky.social
David Hodgson
@dchodge.bsky.social
Researcher at Charité. Interested in mathematically modelling immunity.
🧘🍰🎧🖥️🏃🧪🏳️‍🌈

seroanalytics.org
davidhodgson.me
It serves as a nice reminder to me that some of the most elegant solutions in machine learning and statistics aren't always the newest deep learning architectures. Sometimes, good old Bayesian inference with smart sampling strategies can create something really cool!
October 26, 2025 at 6:53 PM
This visualises how modern statistical inference actually works. RJMCMC explores spaces where we don't even know how many parameters we need, perfect for art, where we don't know in advance how many strokes capture an image.
October 26, 2025 at 6:53 PM
- Proposals are accepted/rejected based on how well they reconstruct your image
- The final painting emerges from thousands of probabilistic decisions
- It's not deterministic, run it twice -> get two different artworks
October 26, 2025 at 6:53 PM
Upload an image, and the algorithms "paints", one probabilistic brushstroke at a time. Each brushstroke represents a "birth" or "death" jump in the model space:
- The algorithm proposes adding new strokes or removing existing ones
October 26, 2025 at 6:52 PM
Haha I actually switched to Claude this week so terse bluesky posts incoming.....
October 2, 2025 at 9:45 AM
AHH cool! I'll have a play with this, doesn't seem active currently tho
October 2, 2025 at 9:43 AM
Cheers Sam! I've not seen this have you got a link? They are fitting ODIN models with monty these days right?
October 2, 2025 at 9:31 AM
Yeah it's actually great, converting the c++ to JavaScript is actually not too bad with a little help from AI !
September 30, 2025 at 4:05 PM
Watch RJMC explore different model dimensions in real-time, use sample data or upload your own CSV.
No installation, just open and experiment. Great for teaching/learning Bayesian model selection!

Package/vignette: dchodge.github.io/rjmc/article...
#statistics #bayesian #MCMC #datascience
Example 1: Mixture model
dchodge.github.io
September 30, 2025 at 12:36 PM
Sure, wanna drop me an email to sort out deets?
September 26, 2025 at 8:01 AM
"2.1. Overview of inference framework" in the methods gives an overview. But basically if you infer an infection you also need to infer an infection time (an extra parameter), no infection then infection time isn't in the framework anymore. Hence need to jump between different dimensions
September 24, 2025 at 4:21 PM
Thanks to everyone who worked on this: @jameshay.bsky.social, Sheikh Jarju, Dawda Jobe, Rhys Wenlock, @adamjkucharski.bsky.social, and @thushan-desilva.bsky.social!
September 23, 2025 at 12:41 PM
It uses reversible jump MCMC to infer missed infections, to help understanding I made a little widget to show you how the fitting process works for simulated data: seroanalytics.org/serojump-widget
Interactive widget for serojump
seroanalytics.org
September 23, 2025 at 12:40 PM
✨ What we did:
- Made a Bayesian model to infer who was infected, when, and how their antibody levels changed
- Validated on both simulations and real-world SARS-CoV-2 data from The Gambia.
- Showed that serojump detects more infections (including sub-threshold ones) and provides richer insights
September 23, 2025 at 12:39 PM
Thanks to every who worked on this! @jameshay.bsky.social, Sheikh Jarju, Dawda Jobe, Rhys Wnelock, @adamjkucharski.bsky.social and @thushan-desilva.bsky.social
September 23, 2025 at 12:32 PM
serojump was designed to be a flexible and pathogen-agnostic solution that can be applied to a wide range of pathogens.

Heres an interactive widget to help with understanding of them reversible jump mcmc methods: lnkd.in/eWGJ39PG
LinkedIn
This link will take you to a page that’s not on LinkedIn
lnkd.in
September 23, 2025 at 12:30 PM
What we did:
- Made a Bayesian model to infer who was infected, when, and how antibody levels changed over time.
- Validated on both simulations and real-world SARS-CoV-2 data from The Gambia.
- Showed that serojump detects more infections (including sub-threshold ones) and provides richer insights
September 23, 2025 at 12:29 PM
Key features:
- WebAssembly-powered performance (10-50x faster than JS)
- Adaptive MCMC for Bayesian inference
- Vaccine intervention analysis with waning immunity
- Real-time convergence diagnostics
- Export data and plots for further analysis
September 19, 2025 at 4:54 PM