Mattan S. Ben-Shachar

Mattan S. Ben-Shachar

@mattansb.msbstats.info

Statistics lecturer | Freelance statistical consultant & research analyst | #rstats dev @easystats.github.io home.msbstats.info (He/Him)

3.7K followers413 following2.6K posts

Why it's important to consult a statistician before data collection, example 17445: If you collect data from 1000 patients, nested in 20 therapists, your effective sample size is much (much!) smaller than you think it is... 😏

People, if you wanna p-hack the shit out of your data, there's no need to pay a statistician - a subscription to the most capable LLM is much cheaper, without any of the pushback. Guess I'm firing a client today 🤷‍♂️

Mattan S. Ben-Shachar reposted

Your monthly reminder that if you're using ChatGPT to do your science, you're failing your colleagues, community, and all of us. Here, ChatGPT makes up data and presents it as the real thing — then apologizes when confronted.

Three different ways of presenting interactions in this little thread. I think "(non)parallel lines" is the most common, but I like the heatmap, especially when there isn't a focal predictor and a moderator and we're really looking to visualize a joint effect.

Peter Ellis@freerangestats.info

There is a very useful graphic that @robin-j-brooks.bsky.social makes repeated use of comparing price elasticity of demand for crude, oil exports from the Gulf and prices. I thought the actual graphic could be improved so had a go at improving it. #rstats code at freerangestats.info/blog/2026/10...

Mattan S. Ben-Shachar reposted

Replying to @mattansb.msbstats.info

You know how the "No brown M&M's" clause in Van Halen's contracts works? (summary: https://en.wikipedia.org/wiki/Van_Halen_test) Well that's what demanding a simulation-based power analysis does for a complicated, e.g. multilevel model: forces you to understand that model properly before showtime.

Mattan S. Ben-Shachar reposted

Replying to @solomonkurz.bsky.social

I actually don’t think you can be a substantive expert without a certain amount of methodological competence. Otherwise you don’t really have a sense of how to interpret your data or the studies of others. It’s just vibes.

As always with AI we need to ask: 1. Is AI good at this? 2. Should we use AI for this? People are often surprised not only by how hard it is to answer (1) but also by how (2) is a completely separate question than (1)!

Mattan S. Ben-Shachar reposted

Replying to @jbakcoleman.bsky.social

Very important for science that you plug a couple of numbers that you made up into the wrong fields in G*Power to get a number that does not change anything, because you’re going to tinker around until it’s the number you want 😌

Mattan S. Ben-Shachar reposted

Just published open access in 𝘗𝘴𝘺𝘤𝘩𝘰𝘭𝘰𝘨𝘪𝘤𝘢𝘭 𝘔𝘦𝘵𝘩𝘰𝘥𝘴: “𝗪𝗼𝗿𝗸𝗶𝗻𝗴 𝘄𝗶𝘁𝗵 𝗖𝗶𝗿𝗰𝘂𝗹𝗮𝗿 𝗗𝗮𝘁𝗮: 𝗔 𝗧𝘂𝘁𝗼𝗿𝗶𝗮𝗹 𝗳𝗼𝗿 𝗖𝗼𝗴𝗻𝗶𝘁𝗶𝘃𝗲 𝗮𝗻𝗱 𝗕𝗲𝗵𝗮𝘃𝗶𝗼𝗿𝗮𝗹 𝗥𝗲𝘀𝗲𝗮𝗿𝗰𝗵” 🔗 doi.org/10.1037/met0... 🙎 Co-authors: @bayslab.org, @ivntmc.bsky.social, @cjungerius.bsky.social, Xiaolu Wang, Julie de Falco, Zahara Gironés, Adam Triabhall

This was a fun one - on mass, people are calibrated predictors (apparently!)

Michael Gilead@michaelgilead.bsky.social

🤠I'm excited to share our new paper, just published in PNAS, in which we examined more than ONE MILLION forecasts from Polymarket, Kalshi etc, The main finding is striking: Prediction markets and collective forecasting platforms are remarkably well calibrated.

Mattan S. Ben-Shachar reposted

🤠I'm excited to share our new paper, just published in PNAS, in which we examined more than ONE MILLION forecasts from Polymarket, Kalshi etc, The main finding is striking: Prediction markets and collective forecasting platforms are remarkably well calibrated.

Mattan S. Ben-Shachar reposted

Why do I want access to all the books & articles? For training, testing & inference. But don't worry, it's 'transformative use'; what comes out will be very different from what I put in. It'll even grow the market for what I'm asking for. No, no, this isn't about LLMs. I'm talking about my students.

Mattan S. Ben-Shachar reposted

Do you want to faithfully quantify false/true positive rates in a significance test? Model the entire data generating process. Faithfully calibrate an estimator? Model the entire data generating process. Design productive experiments? Model the proposed data generating process.

"If you don't open a book or talk to a statistician, you can experience the joy of discovery every day"

Berna Devezer@devezer.bsky.social

"Empirical conclusions depend not only on data but also on analytic decisions" Apparently we know this from... wait for it... many analyst studies. Pro tip: If you don't open a book or talk to a statistician, you can experience the joy of discovery every day 🤯

This is so bad. Why does rendering take 1min but running interactively in #Positron takes upward of 20 minutes??

Mattan S. Ben-Shachar@mattansb.msbstats.info

Is anyone else experiencing extreme variability in @quarto.org interactive run times? Like running `1` can take (within the same session) 0.001s to 1.2 MINUTES. Running in Positron, everything is up to date, and this isn't happening running in the same window just regular R...

Is anyone else experiencing extreme variability in @quarto.org interactive run times? Like running `1` can take (within the same session) 0.001s to 1.2 MINUTES. Running in Positron, everything is up to date, and this isn't happening running in the same window just regular R...

Mattan S. Ben-Shachar reposted

Replying to @gsimpson.bsky.social

Thanks! This inches us toward `glmmTMB` being a replacement for `gamm4` - which, with respect to its authors, I've found a headache to work with (huge model objects, lack of downstream methods, etc.). BUT `glmmTMB` still has issues with predictions, starting values, etc. github.com/glmmTMB/glmm...

github.comopen thread for mgcv smooth issues · Issue #928 · glmmTMB/glmmTMBSee notes. Currently known outstanding issues: setting good default starting values for smooth terms better printing of output (hide fixed terms? print smooth terms in a way more consistent with mg...

🤯

Gavin Simpson@gsimpson.bsky.social

If you fit models with glmmTMB(), gratia 📦 has gained support for these model objects, including glmmTMB's nascent capability for fitting penalized spline terms using mgcv's s() You'll need the GitHub versions of both gratia & glmmTMB to try this out #RStats #statistics github.com/glmmTMB/glmm...

"For observational designs, please describe association, prediction, or covariation in terms of statistical dependence. For example: 'we found that p(smoking, lung cancer) ≠ p(smoking)p(lung cancer)'".

Andrew Gelman et al.@statmodeling.bsky.social

JAMA rules of engagement on causal language statmodeling.stat.columbia.edu/2026/10/12/j...

Mattan S. Ben-Shachar reposted

How should we track human decisions in the kind of data science project that Alex envisions, and how can we ensure LLMs implement our decisions faithfully? One idea would be "Data Analysis Decision Records" What do you think? I'd love any feedback on #DADR ! vincentarelbundock.github.io/dadr

vincentarelbundock.github.ioDADR - DADRData Analysis Decision Records: a file-first format for capturing the choices behind an empirical analysis.
Alexander Wuttke@kunkakom.bsky.social

Perhaps the future of data science coding will be a continuous conversation with coding agents who present us with a series of analytical and coding decisions. We decide, they implement. (And, if we take our work seriously, we then review their implementation.)

Mattan S. Ben-Shachar reposted

What does a sound data analysis workflow look like? In a first step: - Define your estimand (*quantity and unit of interest*) & research question - Map reality to your model (choose variables wisely) How the {modelbased}📦fits into this post-estimation workflow (second step): 👇 #rstats #easystats

Mattan S. Ben-Shachar reposted

Send your best work to PCI Psychology (psych.peercommunityin.org) where it will receive high quality & open peer review free of commercial interference. We review a variety of article types from a wide range of psychological topics (psych.peercommunityin.org/help/help_ge...).

Peer Community In@peercommunityin.bsky.social

1247 preprints have now received a recommendation from one of the 21 thematic PCI! Behind every recommendation is a community of researchers contributing their expertise. Could your preprint be next? 👉 Submit your research to PCI: peercommunityin.org/submit-a-pre...

Mattan S. Ben-Shachar reposted

One thing I find endlessly funny about the rise of AI is that it has revealed that there is a large number of people who believe that the reason they wrote essays at school or university is their teachers were desperately waiting for them to provide a definite answer to “Lear: what’s up with him?”

Dr Dean Burnett@drdeanburnett.bsky.social

"By using AI, tasks like essays that used to take hours can be completed in minutes!" Sure, like how if I arrive at the gym and immediately go for a shower, my workout is done in record time. And if I throw my sandwiches straight in the bin, I can finish my lunch in under 10 seconds.

Remember folks, human peer review guarantees that at least 3-4 humans will read your paper!

Pat Savage@patrickesavage.bsky.social

This is good, but I think missing a crucial point: the goal of peer review is not just to publish the most accurate and novel papers possible. It also has a social function: reviewers are part of the process of creating and transmitting knowledge to other humans. www.science.org/content/arti...

Mattan S. Ben-Shachar reposted

Outside of the obvious open source problems with vibe coding, there is soooo much truth in the “now I have to read/review all of this stuff with my brain power when you used almost none at all” across all layers of work now. Feel this in my bones 😭

Kybosh@kybosh.bsky.social

I like seeing the dev of the SNES core on the Pocket actually telling one of these dudes off. Holy shit.