Aki Vehtari
@avehtari.bsky.social
Professor in computational Bayesian modeling, Aalto University, Finland. Co-author of Bayesian Data Analysis 3rd ed, Regression and Other Stories, Active Statistics and Bayesian Workflow. #mcmc_stan and #arviz developer. https://users.aalto.fi/ave/
Known as the "saviour of mothers", Ignac Semmelweis pioneered handwashing in hospitals, saving countless lives. Can we apply modern statistical techniques to his own data? New and free to read: buff.ly/4NUSgLc
Anyone ever use the geometric Poisson distribution? If I've implemented it correctly in Stan, it's giving me better fits than negative binomial according to PSIS-LOO-CV with a big count occupancy model.
New blog post! Odds ratios are...a bit weird. Here I explain two problems (interpretation, non-collapsibility) and provide some simple recommendations for improved reporting. www.the100.ci/2026/07/30/r...
Reviewer notes: Odds ratios are really odd
When psychological researchers investigate binary outcomes, they routinely report odds ratios to quantify the strength of an effect or an association. This is quite understandable given that psycholog...
the100.ci
For examples of the priorsense package in use, see e.g. chapter 17 case study ("sleep study") from the Bayesian Workflow website: avehtari.github.io/Bayesian-Wor...
priorsense R package has now JOSS paper "priorsense: Efficient prior and likelihood sensitivity checks for Bayesian models in R" you can cite, too doi.org/10.21105/jos... with Noa Kallioinen, Topi Paananen, and @paulbuerkner.com priorsense achieved also a gold badge from @ropensci.org review!
priorsense R package has now JOSS paper "priorsense: Efficient prior and likelihood sensitivity checks for Bayesian models in R" you can cite, too doi.org/10.21105/jos... with Noa Kallioinen, Topi Paananen, and @paulbuerkner.com priorsense achieved also a gold badge from @ropensci.org review!
priorsense: Efficient prior and likelihood sensitivity checks for Bayesian models in R
Kallioinen et al., (2026). priorsense: Efficient prior and likelihood sensitivity checks for Bayesian models in R. Journal of Open Source Software, 11(123), 11036, https://doi.org/10.21105/joss.11036
doi.org
The maximum length of bsky post is 300 chars. The length of Bayesian Workflow book is about 1.6 million chars.
Anna Freni-Sterrantino, Janet van Niekerk, Elias Teixeira Krainski, Denis Rustand, Haziq Jamil, H{\aa}vard Rue Informative Distance-Based Priors for Correlation Matrices Centred on a Target Reference https://arxiv.org/abs/2607.18926
After a couple of months hiatus, a new blog post on directly parameterizing structural zeros in correlation matrices. spinkney.github.io/posts/post-1...
Structural Zeros in Correlation Matrices: A Twelve-Parameterization Bake-Off – Pinkney’s Sufficient Stats
spinkney.github.io
Reviews of our Bayesian Workflow book from Bin Yu, David Spiegelhalter, Brad Efron, Christian Robert, Rohan Alexander, and Mine Doğucu! statmodeling.stat.columbia.edu/2026/07/16/r...
Reviews of our Bayesian Workflow book from Bin Yu, David Spiegelhalter, Brad Efron, Christian Robert, Rohan Alexander, and Mine Doğucu! | Statistical Modeling, Causal Inference, and Social Science
statmodeling.stat.columbia.edu
Just got my author copy of Bayesian workflow! Check out avehtari.github.io/Bayesian-Wor... if you want a copy, a discount code, get source code for our examples and stuff.
Osvaldo is translating the Bayesian Workflow book's case studies to Python, very useful in case you are snake person arviz-devs.github.io/bayesian-wor...
Look what was waiting on my desk this morning! It's so great to finally see #BayesianWorkflow in print.
Finally, got a copy of Bayesian workflow book in my hand, and it looks awesome! I really like we did get full colors for figures, too
18 Associate Editors resign from Statistics and Computing editorial board: Problems with commercial scholarly publishing, and what does this all mean? statmodeling.stat.columbia.edu/2026/07/10/1...
18 Associate Editors resign from Statistics and Computing editorial board: Problems with commercial scholarly publishing, and what does this all mean? | Statistical Modeling, Causal Inference, and S...
statmodeling.stat.columbia.edu
If the editors regroup elsewhere to form a new journal, they hope to publish with a society, Ryder told us, citing journals like Journal of the Royal Statistical Society and Annals of Statistics, “none of which force authors to pay APCs.”
‘The exploitation still remains’: Stats journal associate editors resign over $3,000 publishing charge
Eighteen associate editors of the journal Statistics and Computing have announced they will resign after Springer Nature announced the journal would require a fee to publish. In a July 8 stat…
retractionwatch.com
retractionwatch.com/2026/07/09/t... Well done editors!
Looking forward to teaching the nowcasting half of our nowcasting and forecast course at SISMID starting today! Some nice (I hope) new content on modelling workflows vibing on the Bayesian workflow book from @avehtari.bsky.social et al. and new session on complex reporting processes.
Nowcasting infectious disease dynamics - SISMID – SISMID: Nowcasting
Nowcasting infectious disease dynamics - SISMID
nfidd.github.io
📘 With the release of our textbook "Bayesian Workflow" (avehtari.github.io/Bayesian-Wor...), I figured I'd also share the content of my graduate course on the topic at UBC. 🌎 charlesm93.github.io/stat547/ The course contains overlapping and complementary material, homeworks and reading.
Bayesian Workflow book: Website – Bayesian Workflow book
Website for the Bayesian Workflow book by Gelman, Vehtari, McElreath, et al. — case studies, code, and exercises in R and Stan.
avehtari.github.io
The new loo package CRAN release v2.10.0 has new loo_compare() data.frame output with columns p_worse, diag_diff and diag_elpd, based on paper "Uncertainty in Bayesian leave-one-out cross-validation based model comparison" doi.org/10.1214/25-B... See examples at users.aalto.fi/~ave/casestu...
@aloctavodia.bsky.social has been porting Bayesian Workflow book avehtari.github.io/Bayesian-Wor... case studies to Python using CmdStanPy, numpyro, ArviZ, Bambi, and kulprit arviz-devs.github.io/bayesian-wor... He is working on porting the rest of the case studies, too
Bayesian Workflow book: Case studies in Python – Bayesian Workflow case studies in Python
arviz-devs.github.io
posterior R package has now JOSS paper you can cite, too joss.theoj.org/papers/10.21... with @paulbuerkner.com , Jonah Gabry, @mjskay.com
posterior: Tools for Working with Posterior Distributions in R
Bürkner et al., (2026). posterior: Tools for Working with Posterior Distributions in R. Journal of Open Source Software, 11(122), 10526, https://doi.org/10.21105/joss.10526
joss.theoj.org
Excellent paper and I fully agree with their conclusions. We had similar unpublished experimental results but ended up prioritizing other projects. This is a more extensive study of the issue and happy to see it published! @bayesianstats.bsky.social
arXiv📈🤖 Exploring Pareto smoothing in sequential Monte Carlo By Tan, Walker, Everitt
If you are going to ISBA meeting, you can talk with Anna and @davidkohns.bsky.social about this paper!
New paper "To select or not to select: predictively consistent priors instead of model selection" with Anna Elisabeth Riha, Leevi Lindgren, @davidkohns.bsky.social, @paulbuerkner.com arxiv.org/abs/2606.22850 Model selection is not a substitute for building good models in the first place 1/
📦 The {BayesFR} package is now on CRAN! It allows fitting functional responses by providing dynamical prediction models for use in #brms. Includes many trophic interaction models, and now also multi-species models. #Rstats (1/3)
BayesFR: Fitting Functional Responses in 1- and 2-Prey Systems
Easy application of Bayesian inference for functional responses via 'brms'. This package allows to fit various FR models for single- and multi-prey experiments by providing nonlinear prediction functi...
cran.r-project.org
"We study when model selection is unnecessary or can even be harmful for predictive performance in finite data regimes and.. need for selecting simpler models can depend on prior choice..predictively consistent priors, which keep prior predictive implications stable as model complexity increases." 🧪
New paper "To select or not to select: predictively consistent priors instead of model selection" with Anna Elisabeth Riha, Leevi Lindgren, @davidkohns.bsky.social, @paulbuerkner.com arxiv.org/abs/2606.22850 Model selection is not a substitute for building good models in the first place 1/
New paper "To select or not to select: predictively consistent priors instead of model selection" with Anna Elisabeth Riha, Leevi Lindgren, @davidkohns.bsky.social, @paulbuerkner.com arxiv.org/abs/2606.22850 Model selection is not a substitute for building good models in the first place 1/
Our paper (with Alain Durmus, Samuel Gruffaz, Miika Kailas and Eero Saksman) on the ergodicity of dynamic path length HMC algorithms appeared in the AAP: doi.org/10.1214/25-A.... The results accommodate the 'biased progressive sampling' path selection used in @mc-stan.org.
doi.org
Picked this up today for some light summer reading! Looking forward to diving in. Hope to understand at least 25% of it. @rmcelreath.bsky.social @avehtari.bsky.social
new diamond open-access Journal of Statistical Ecology launched 🎉🎉🎉 jse.centre-mersenne.org @fredbarraquand.bsky.social @oaggimenez.bsky.social @marieaugermethe.bsky.social @vianeylb.bsky.social (apologies to any Bsky editors I missed)
Journal of Statistical Ecology Journal of Statistical Ecology
jse.centre-mersenne.org
We built an integrated population dynamics model. This time for Baltic grey seals. It was just published Bayesian integrated population model of Baltic grey seals informs on population carrying capacity and the impact of Baltic herring on reproduction. www.sciencedirect.com/science/arti... 1/4
sciencedirect.com