Aki Vehtari
@avehtari.bsky.social
Academy Professor in computational Bayesian modeling at Aalto University, Finland. Bayesian Data Analysis 3rd ed, Regression and Other Stories, and Active Statistics co-author. #mcmc_stan and #arviz developer.
Web page https://users.aalto.fi/~ave/
Web page https://users.aalto.fi/~ave/
Pinned
Aki Vehtari
@avehtari.bsky.social
· Aug 2
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...
- #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...
Reposted by Aki Vehtari
This time I try to explain group-level confounding and some ways to deal with it. Lecture B04 of Statistical Rethinking 2026 - fixed effects, Mundlak machines, latent Mundlak machines, intro to social network analysis and the social relations model. Full lecture list: github.com/rmcelreath/s...
Statistical Rethinking 2026 Lecture B04 - Group-level confounding and intro to social networks
YouTube video by Richard McElreath
www.youtube.com
January 30, 2026 at 1:27 PM
This time I try to explain group-level confounding and some ways to deal with it. Lecture B04 of Statistical Rethinking 2026 - fixed effects, Mundlak machines, latent Mundlak machines, intro to social network analysis and the social relations model. Full lecture list: github.com/rmcelreath/s...
Reposted by Aki Vehtari
wanna learn about cognitive modeling and love pizza? I am revising my cognitive modeling course notes and could use some feedback (or you might just enjoy learning about cog modeling in R and Stan): fusaroli.github.io/AdvancedCogn...
(only chapter 1-3 are in place, the others will come)
(only chapter 1-3 are in place, the others will come)
Chapter 2 The Pizza Experiment | Advanced Cognitive Modeling Notes
My notes for the advanced cognitive modeling course - 2026
fusaroli.github.io
January 30, 2026 at 9:08 AM
wanna learn about cognitive modeling and love pizza? I am revising my cognitive modeling course notes and could use some feedback (or you might just enjoy learning about cog modeling in R and Stan): fusaroli.github.io/AdvancedCogn...
(only chapter 1-3 are in place, the others will come)
(only chapter 1-3 are in place, the others will come)
Reposted by Aki Vehtari
StanCon 2026 is this August 17-21 in Upsala, Sweden 🇸🇪
www.stancon2026.org
⏰ Abstracts for contributed talks are due Feb 25
⏰ Abstracts for posters are due May 27
And just to be clear: Yes, StanCon is my favorite conference to attend!! Can't wait for this one!
www.stancon2026.org
⏰ Abstracts for contributed talks are due Feb 25
⏰ Abstracts for posters are due May 27
And just to be clear: Yes, StanCon is my favorite conference to attend!! Can't wait for this one!
January 29, 2026 at 9:55 PM
StanCon 2026 is this August 17-21 in Upsala, Sweden 🇸🇪
www.stancon2026.org
⏰ Abstracts for contributed talks are due Feb 25
⏰ Abstracts for posters are due May 27
And just to be clear: Yes, StanCon is my favorite conference to attend!! Can't wait for this one!
www.stancon2026.org
⏰ Abstracts for contributed talks are due Feb 25
⏰ Abstracts for posters are due May 27
And just to be clear: Yes, StanCon is my favorite conference to attend!! Can't wait for this one!
Reposted by Aki Vehtari
if you want to know how to compute marginal means from a mixed effects model in brms using rvars, then have I got a supplemental materials document for you pubs.asha.org/doi/10.1044/...
Does the Use of Crowdsourced Listeners Yield Different Speech Intelligibility Results Than In-Person Listeners for Typically Developing Children?
Purpose: We examined the performance of crowdsourced listeners compared with in-person
listeners on the measurement of speech intelligibility for...
pubs.asha.org
January 29, 2026 at 10:10 PM
if you want to know how to compute marginal means from a mixed effects model in brms using rvars, then have I got a supplemental materials document for you pubs.asha.org/doi/10.1044/...
Reposted by Aki Vehtari
Another absolute banger from @natehaines.bsky.social: generative hierarchical Bayesian modeling* is the best way to investigate individual differences!
*This isn't "just" making use of Bayesian estimation, but one of the best examples I've seen of a full Bayesian embrace of uncertainty.
*This isn't "just" making use of Bayesian estimation, but one of the best examples I've seen of a full Bayesian embrace of uncertainty.
1/9 New blog is live! This is part 2 of a series—last time we looked at the Dunning-Kruger effect, now we are digging in to Implicit vs Explicit attitudes and the Implicit Association Test. To start, of course we need a good meme...
haines-lab.com/post/part-2-...
haines-lab.com/post/part-2-...
January 29, 2026 at 8:08 AM
Another absolute banger from @natehaines.bsky.social: generative hierarchical Bayesian modeling* is the best way to investigate individual differences!
*This isn't "just" making use of Bayesian estimation, but one of the best examples I've seen of a full Bayesian embrace of uncertainty.
*This isn't "just" making use of Bayesian estimation, but one of the best examples I've seen of a full Bayesian embrace of uncertainty.
Reposted by Aki Vehtari
1/9 New blog is live! This is part 2 of a series—last time we looked at the Dunning-Kruger effect, now we are digging in to Implicit vs Explicit attitudes and the Implicit Association Test. To start, of course we need a good meme...
haines-lab.com/post/part-2-...
haines-lab.com/post/part-2-...
January 26, 2026 at 5:45 PM
1/9 New blog is live! This is part 2 of a series—last time we looked at the Dunning-Kruger effect, now we are digging in to Implicit vs Explicit attitudes and the Implicit Association Test. To start, of course we need a good meme...
haines-lab.com/post/part-2-...
haines-lab.com/post/part-2-...
Reposted by Aki Vehtari
All my #rstats ebooks are now in the quarto format, and hosted on Quarto Pub. Their old bookdown links will all be dead by the weekend.
1/3
1/3
January 28, 2026 at 3:34 PM
All my #rstats ebooks are now in the quarto format, and hosted on Quarto Pub. Their old bookdown links will all be dead by the weekend.
1/3
1/3
Reposted by Aki Vehtari
Deadline for StanCon 2026 tutorials and workshops (@mc-stan) is today (anywhere on earth). More information here:
discourse.mc-stan.org/t/stancon-20...
discourse.mc-stan.org/t/stancon-20...
StanCon 2026 Tutorials and Workshop deadline today (AoE)
Hi everyone, The submission deadline for contributing tutorials and workshops is today (anywhere on earth). Tutorial Tutorials provide hands-on learning experiences to help attendees build practica...
discourse.mc-stan.org
January 28, 2026 at 10:12 AM
Deadline for StanCon 2026 tutorials and workshops (@mc-stan) is today (anywhere on earth). More information here:
discourse.mc-stan.org/t/stancon-20...
discourse.mc-stan.org/t/stancon-20...
Our CS department could be a great fit for you, too! Although in the call there is interest in particular topics, all areas of CS are considered including computational Bayes, ML, AI, etc. So worth trying if working in those areas, too
Aalto University is looking for an Assistant Professor in Computer Science, application deadline February 2, 2026!
www.aalto.fi/en/open-posi...
www.aalto.fi/en/open-posi...
January 26, 2026 at 4:38 PM
Our CS department could be a great fit for you, too! Although in the call there is interest in particular topics, all areas of CS are considered including computational Bayes, ML, AI, etc. So worth trying if working in those areas, too
Bayesian Workflow by
Andrew Gelman, Aki Vehtari, @rmcelreath.bsky.social with @danpsimpson.bsky.social, @charlesm993.bsky.social, @yulingy.bsky.social, Lauren Kennedy, Jonah Gabry, @paulbuerkner.com, @modrakm.bsky.social, @vianeylb.bsky.social
(in production, estimated copy-editing time 6 weeks)
Andrew Gelman, Aki Vehtari, @rmcelreath.bsky.social with @danpsimpson.bsky.social, @charlesm993.bsky.social, @yulingy.bsky.social, Lauren Kennedy, Jonah Gabry, @paulbuerkner.com, @modrakm.bsky.social, @vianeylb.bsky.social
(in production, estimated copy-editing time 6 weeks)
January 26, 2026 at 8:18 AM
Bayesian Workflow by
Andrew Gelman, Aki Vehtari, @rmcelreath.bsky.social with @danpsimpson.bsky.social, @charlesm993.bsky.social, @yulingy.bsky.social, Lauren Kennedy, Jonah Gabry, @paulbuerkner.com, @modrakm.bsky.social, @vianeylb.bsky.social
(in production, estimated copy-editing time 6 weeks)
Andrew Gelman, Aki Vehtari, @rmcelreath.bsky.social with @danpsimpson.bsky.social, @charlesm993.bsky.social, @yulingy.bsky.social, Lauren Kennedy, Jonah Gabry, @paulbuerkner.com, @modrakm.bsky.social, @vianeylb.bsky.social
(in production, estimated copy-editing time 6 weeks)
Publisher's copy-editing for the Bayesian Workflow book has started
January 23, 2026 at 7:45 PM
Publisher's copy-editing for the Bayesian Workflow book has started
Reposted by Aki Vehtari
Adventures in Covariance - Lecture B03 of Statistical Rethinking 2026. Prelude about MCMC effective sample size, Multilevel varying slopes models with correlated features, non-centered parameterizations for covariance models, model expansion workflow. Next week is social networks.
Statistical Rethinking Lecture B03 - Adventures in Covariance
YouTube video by Richard McElreath
www.youtube.com
January 23, 2026 at 1:22 PM
Adventures in Covariance - Lecture B03 of Statistical Rethinking 2026. Prelude about MCMC effective sample size, Multilevel varying slopes models with correlated features, non-centered parameterizations for covariance models, model expansion workflow. Next week is social networks.
Juho Timonen defended his thesis succesfully 🎉 (the thesis includes two papers I helped with: speeding up ODEs with importance sampling dx.doi.org/10.1002/sta4... and longitudinal GPs doi.org/10.1093/bioi...). Photo includes supervisor Harri Lähdesmäki and the opponent @mrattray.bsky.social
January 23, 2026 at 2:14 PM
Juho Timonen defended his thesis succesfully 🎉 (the thesis includes two papers I helped with: speeding up ODEs with importance sampling dx.doi.org/10.1002/sta4... and longitudinal GPs doi.org/10.1093/bioi...). Photo includes supervisor Harri Lähdesmäki and the opponent @mrattray.bsky.social
Reposted by Aki Vehtari
StanCon 2026 tutorial and workshop deadlines in one week:
discourse.mc-stan.org/t/stancon-20...
@mc-stan.org
discourse.mc-stan.org/t/stancon-20...
@mc-stan.org
StanCon 2026 Deadline for tutorial and workshop in one week
Hi everyone, The submission deadline for contributing tutorials and workshops is one week from now, on the 28th of January. Tutorial Tutorials provide hands-on learning experiences to help attendee...
discourse.mc-stan.org
January 21, 2026 at 9:20 AM
StanCon 2026 tutorial and workshop deadlines in one week:
discourse.mc-stan.org/t/stancon-20...
@mc-stan.org
discourse.mc-stan.org/t/stancon-20...
@mc-stan.org
Reposted by Aki Vehtari
February 5th in Bayesian Data Analysis Meetup virtual event:
Bayesian Models in Production by Ian Costley (Wegmans Food Markets)
...hands-on experience deploying Bayesian models built with Stan and PyMC into real production systems...
see more at discourse.mc-stan.org/t/feb-5th-ba...
Bayesian Models in Production by Ian Costley (Wegmans Food Markets)
...hands-on experience deploying Bayesian models built with Stan and PyMC into real production systems...
see more at discourse.mc-stan.org/t/feb-5th-ba...
Feb 5th Bayesian Data Analysis Meetup Virtual Event
Hi All, On Feb 5 we have a virtual event for the Bayesian Data Analysis Meetup. We’re excited to host Ian Costley (Wegmans Food Markets) for an upcoming talk on Bayesian Models in Production. Ian wi...
discourse.mc-stan.org
January 20, 2026 at 12:15 PM
February 5th in Bayesian Data Analysis Meetup virtual event:
Bayesian Models in Production by Ian Costley (Wegmans Food Markets)
...hands-on experience deploying Bayesian models built with Stan and PyMC into real production systems...
see more at discourse.mc-stan.org/t/feb-5th-ba...
Bayesian Models in Production by Ian Costley (Wegmans Food Markets)
...hands-on experience deploying Bayesian models built with Stan and PyMC into real production systems...
see more at discourse.mc-stan.org/t/feb-5th-ba...
Reposted by Aki Vehtari
May 11, Short Course on Bayesian Causal Inference with Stan, Stress-Testing Assumptions: Bayesian Methods for Sensitivity Analysis in Causal Inference, in-person at the American Causal Inference Conference meeting in Salt Lake City. See more at discourse.mc-stan.org/t/upcoming-s...
Upcoming Short Course on Bayesian Causal Inference with Stan
Hi all, I wanted to publicize a short course I’ll be teaching on topics related to Bayesian causal inference. See below for course title, abstract, outline, and other information. The course will be...
discourse.mc-stan.org
January 20, 2026 at 12:19 PM
May 11, Short Course on Bayesian Causal Inference with Stan, Stress-Testing Assumptions: Bayesian Methods for Sensitivity Analysis in Causal Inference, in-person at the American Causal Inference Conference meeting in Salt Lake City. See more at discourse.mc-stan.org/t/upcoming-s...
I just finished revising the last case study code for the Bayesian Workflow book, which was bigger effort than I expected as I had to do a big revision of the corresponding book chapter, too. Now we are close to being finished
During the last few weeks, Jonah Gabry and I have been reviewing and improving more than 14k lines of code for the Bayesian Workflow book. Still some things to fix, but soon ready
We're doing the final sprint, and I think we're able to send the PDF of the forthcoming Bayesian Workflow book to the publisher in the next two weeks (500+ pages), which would mean it would be published some time next year
January 16, 2026 at 6:25 PM
I just finished revising the last case study code for the Bayesian Workflow book, which was bigger effort than I expected as I had to do a big revision of the corresponding book chapter, too. Now we are close to being finished
Reposted by Aki Vehtari
Lecture B02 of Statistical Rethinking 2026. Multilevel model expansion: workflow, cluster and feature engineering, non-centered parameterization, dank memes. Continues next week with models of population covariance and (if there is time) group-level confounding and "Mundlak machines".
Statistical Rethinking 2026 - Lecture B02 - Multilevel Model Expansion
YouTube video by Richard McElreath
www.youtube.com
January 16, 2026 at 12:11 PM
Lecture B02 of Statistical Rethinking 2026. Multilevel model expansion: workflow, cluster and feature engineering, non-centered parameterization, dank memes. Continues next week with models of population covariance and (if there is time) group-level confounding and "Mundlak machines".
Reposted by Aki Vehtari
There is a very cool postdoc position in the EnvStat group supervised by Elina Numminen.
jobs.helsinki.fi/job/Helsinki...
jobs.helsinki.fi/job/Helsinki...
Postdoctoral Researcher in Statistical Ecology and Evolution
Postdoctoral Researcher in Statistical Ecology and Evolution
jobs.helsinki.fi
January 15, 2026 at 10:56 AM
There is a very cool postdoc position in the EnvStat group supervised by Elina Numminen.
jobs.helsinki.fi/job/Helsinki...
jobs.helsinki.fi/job/Helsinki...
Reposted by Aki Vehtari
wikipedia turns 25 today! the last unenshittified major website! backbone of online info! triumph of humanity! powered by urge of unpaid randos to correct each other! somehow mostly reliable! "good thing wikipedia works in practice, because it sure doesn't work in theory" - old wiki adage
January 15, 2026 at 1:47 PM
wikipedia turns 25 today! the last unenshittified major website! backbone of online info! triumph of humanity! powered by urge of unpaid randos to correct each other! somehow mostly reliable! "good thing wikipedia works in practice, because it sure doesn't work in theory" - old wiki adage
Reposted by Aki Vehtari
The 0.5.0 version of my {brms} + {tidyverse} translation of McElreath's "Statistical Rethinking" (2nd ed) is up!
solomon.quarto.pub/sr2/
1/3
#rstats
solomon.quarto.pub/sr2/
1/3
#rstats
Statistical rethinking 2 with rstan and the tidyverse
solomon.quarto.pub
January 14, 2026 at 3:08 PM
The 0.5.0 version of my {brms} + {tidyverse} translation of McElreath's "Statistical Rethinking" (2nd ed) is up!
solomon.quarto.pub/sr2/
1/3
#rstats
solomon.quarto.pub/sr2/
1/3
#rstats
Reposted by Aki Vehtari
📖 Big news! We just released the first five chapters of our new book, Hello Data Science. It is a fully open-access resource written for beginners. Please help us spread the word! A few points about the book are below 👇
🔗 www.hellodata.science
#rstats #datascience #tidyverse
🔗 www.hellodata.science
#rstats #datascience #tidyverse
January 14, 2026 at 5:34 AM
📖 Big news! We just released the first five chapters of our new book, Hello Data Science. It is a fully open-access resource written for beginners. Please help us spread the word! A few points about the book are below 👇
🔗 www.hellodata.science
#rstats #datascience #tidyverse
🔗 www.hellodata.science
#rstats #datascience #tidyverse
Reposted by Aki Vehtari
FDA drugs and biologics guidance for Bayesian clinical trials is something I've been dreaming of for decades. I am thrilled that this draft has been released!! #Statistics #StatsSky #fda #clinicaltrial #bayes
This is a big deal for speeding up clinical trials, and for pediatric use after adult trials have proved successful. The @USFDA goes Bayesian.
A win for #IBD patients, and especially for kids with #IBD. @crohnsandcolitisau.bsky.social @f2harrell.bsky.social
www.fda.gov/news-events/...
A win for #IBD patients, and especially for kids with #IBD. @crohnsandcolitisau.bsky.social @f2harrell.bsky.social
www.fda.gov/news-events/...
FDA Issues Guidance on Modernizing Statistical Methods for Clinical Trials
The U.S. Food and Drug Administration today published draft guidance designed to facilitate the use of Bayesian methodologies in clinical trials of drugs and biologics, helping drug developers make be...
www.fda.gov
January 13, 2026 at 4:07 PM
FDA drugs and biologics guidance for Bayesian clinical trials is something I've been dreaming of for decades. I am thrilled that this draft has been released!! #Statistics #StatsSky #fda #clinicaltrial #bayes
Reposted by Aki Vehtari
I biked to work in 3cm of slush this morning to deliver another lecture. Stat Rethinking A02: more Bayesian updating, points and intervals, posterior predictive distributions. Next week it's linear regression as Gauss intended. Full course schedule here: github.com/rmcelreath/s...
Statistical Rethinking 2026 - Lecture A02 - Garden of Forking Data
YouTube video by Richard McElreath
www.youtube.com
January 13, 2026 at 1:14 PM
I biked to work in 3cm of slush this morning to deliver another lecture. Stat Rethinking A02: more Bayesian updating, points and intervals, posterior predictive distributions. Next week it's linear regression as Gauss intended. Full course schedule here: github.com/rmcelreath/s...
Reposted by Aki Vehtari
Release of CmdStan 2.38
We are very happy to announce that the 2.38.0 release of CmdStan is now available on Github! As usual, the release of CmdStan is accompanied by new releases of Stan Math, core Stan, and Stanc3. This release cycle focused on stability and usability improvements, with a few…
We are very happy to announce that the 2.38.0 release of CmdStan is now available on Github! As usual, the release of CmdStan is accompanied by new releases of Stan Math, core Stan, and Stanc3. This release cycle focused on stability and usability improvements, with a few…
Release of CmdStan 2.38
We are very happy to announce that the 2.38.0 release of CmdStan is now available on Github! As usual, the release of CmdStan is accompanied by new releases of Stan Math, core Stan, and Stanc3. This release cycle focused on stability and usability improvements, with a few new features and a lot of work under the hood for upcoming features.
blog.mc-stan.org
January 13, 2026 at 5:50 PM
Release of CmdStan 2.38
We are very happy to announce that the 2.38.0 release of CmdStan is now available on Github! As usual, the release of CmdStan is accompanied by new releases of Stan Math, core Stan, and Stanc3. This release cycle focused on stability and usability improvements, with a few…
We are very happy to announce that the 2.38.0 release of CmdStan is now available on Github! As usual, the release of CmdStan is accompanied by new releases of Stan Math, core Stan, and Stanc3. This release cycle focused on stability and usability improvements, with a few…