Magnus Johansson
@pgmj.bsky.social
PhD & lic. psychologist. Research specialist at Karolinska Institutet. R package for Rasch psychometrics: pgmj.github.io/easyRasch/
#openscience, #prevention, #psychometrics, #rstats, #photo
#openscience, #prevention, #psychometrics, #rstats, #photo
Pinned
Magnus Johansson
@pgmj.bsky.social
· Mar 11
Detecting item misfit in Rasch models
pgmj.github.io
My simulation study on item misfit detection in Rasch models is published. We should leave rule-of-thumb critical values for GOF metrics behind us and use simulation/bootstrap methods to determine cutoffs appropriate for the data and items being analyzed. pgmj.github.io/rasch_itemfit/ #psychometrics
Reposted by Magnus Johansson
Two-group pre/post data are deceptively simple, and you could analyze them in many different ways, depending on your goals. Here are three blog posts on the topic:
solomonkurz.netlify.app/blog/2022-06...
solomonkurz.netlify.app/blog/2020-12...
solomonkurz.netlify.app/blog/2023-06...
solomonkurz.netlify.app/blog/2022-06...
solomonkurz.netlify.app/blog/2020-12...
solomonkurz.netlify.app/blog/2023-06...
November 10, 2025 at 7:19 PM
Two-group pre/post data are deceptively simple, and you could analyze them in many different ways, depending on your goals. Here are three blog posts on the topic:
solomonkurz.netlify.app/blog/2022-06...
solomonkurz.netlify.app/blog/2020-12...
solomonkurz.netlify.app/blog/2023-06...
solomonkurz.netlify.app/blog/2022-06...
solomonkurz.netlify.app/blog/2020-12...
solomonkurz.netlify.app/blog/2023-06...
Reposted by Magnus Johansson
“…the net worth of the 10 richest US billionaires grew by $698bn in the past year. That money alone, the increment in the wealth of 10 people, is almost 10 times the annual amount required to end extreme poverty worldwide.”
www.theguardian.com/commentisfre...
www.theguardian.com/commentisfre...
I wish we could ignore Bill Gates on the climate crisis. But he’s a billionaire, so we can’t | George Monbiot
Money talks – and his essay denouncing ‘near-term emissions goals’ at Cop30 mostly argues the case for letting the ultra-rich off the hook
www.theguardian.com
November 8, 2025 at 11:16 AM
“…the net worth of the 10 richest US billionaires grew by $698bn in the past year. That money alone, the increment in the wealth of 10 people, is almost 10 times the annual amount required to end extreme poverty worldwide.”
www.theguardian.com/commentisfre...
www.theguardian.com/commentisfre...
Reposted by Magnus Johansson
Meta earns $3.5 billion every six months from showing Faceboon and Instagram users 15 billion “higher legal risk” scam ad impressions a day, internal documents state.
That haul vastly exceeds how much the company expects regulators
To fine it for running scam ads.
www.reuters.com/investigatio...
That haul vastly exceeds how much the company expects regulators
To fine it for running scam ads.
www.reuters.com/investigatio...
www.reuters.com
November 6, 2025 at 11:46 AM
Meta earns $3.5 billion every six months from showing Faceboon and Instagram users 15 billion “higher legal risk” scam ad impressions a day, internal documents state.
That haul vastly exceeds how much the company expects regulators
To fine it for running scam ads.
www.reuters.com/investigatio...
That haul vastly exceeds how much the company expects regulators
To fine it for running scam ads.
www.reuters.com/investigatio...
Waiting for a new work Mac, I’m using an M1 Air 2020 which only has 4 high performance cores. Running some tests in R, the Air is twice as fast when using only 4 cores compared to using 8 cores (including the high efficiency cores).
November 5, 2025 at 11:49 AM
Waiting for a new work Mac, I’m using an M1 Air 2020 which only has 4 high performance cores. Running some tests in R, the Air is twice as fast when using only 4 cores compared to using 8 cores (including the high efficiency cores).
I was just notified of another paper citing our paper as validating the Swedish PSS-4, when we actually conclude that it should not be used. What was even more surprising was that one of my coauthors on the psychometrics paper was also a coauthor on the paper. Not sure what to do with this.
A recent paper using the 4-item perceived stress scale is citing our PSS #psychometrics paper in the methods section. From our abstract: “the PSS-4 was not deemed suitable as a unidimensional scale”. They didn’t even read the abstract?! doi.org/10.1186/s128...
journals.sagepub.com/doi/full/10....
journals.sagepub.com/doi/full/10....
November 3, 2025 at 9:07 AM
I was just notified of another paper citing our paper as validating the Swedish PSS-4, when we actually conclude that it should not be used. What was even more surprising was that one of my coauthors on the psychometrics paper was also a coauthor on the paper. Not sure what to do with this.
Reposted by Magnus Johansson
AI has an "emperor has no clothes" problem where people imagine there are geniuses who will inevitably achieve breakthroughs with enough cash.
AI is bottlenecked by limits in data availability, statistical mechanics, & computing. Improvements will be expensive & incremental, not fundamental.
AI is bottlenecked by limits in data availability, statistical mechanics, & computing. Improvements will be expensive & incremental, not fundamental.
so @matteowong.bsky.social & I wrote on data centers: arguably the most important buildings in the world & are, in a way, holding the economy hostage. Byzantine financial instruments, private equity, depreciating tech, hype, $trillion valuations. it’s all there. an ai crash prob starts here.
Here’s How the AI Crash Happens
The U.S. is becoming an Nvidia-state.
www.theatlantic.com
October 31, 2025 at 1:05 PM
AI has an "emperor has no clothes" problem where people imagine there are geniuses who will inevitably achieve breakthroughs with enough cash.
AI is bottlenecked by limits in data availability, statistical mechanics, & computing. Improvements will be expensive & incremental, not fundamental.
AI is bottlenecked by limits in data availability, statistical mechanics, & computing. Improvements will be expensive & incremental, not fundamental.
Forced to deal with Microsoft Outlook/etc at work, I constantly find the default settings to be annoying/stupid. I wonder if they ever gather data to understand user preferences or just make assumptions. Or am I the outlier?
a cartoon of a man in a suit and tie standing in front of a fire escape
ALT: a cartoon of a man in a suit and tie standing in front of a fire escape
media.tenor.com
October 31, 2025 at 10:38 AM
Forced to deal with Microsoft Outlook/etc at work, I constantly find the default settings to be annoying/stupid. I wonder if they ever gather data to understand user preferences or just make assumptions. Or am I the outlier?
Reposted by Magnus Johansson
I'm now also looking for a postdoc with strong Bayesian background and interest in developing Bayesian cross-validation theory, methods and software. Apply by email with no specific deadline (see contact information at users.aalto.fi/~ave/).
Others, please share
Others, please share
I'm looking for a doctoral student with Bayesian background to work on Bayesian workflow and cross-validation (see my publication list users.aalto.fi/~ave/publica... for my recent work) at Aalto University.
Apply through the ELLIS PhD program (dl October 31) ellis.eu/news/ellis-p...
Apply through the ELLIS PhD program (dl October 31) ellis.eu/news/ellis-p...
ELLIS PhD Program: Call for Applications 2025
The ELLIS mission is to create a diverse European network that promotes research excellence and advances breakthroughs in AI, as well as a pan-European PhD program to educate the next generation of AI...
ellis.eu
October 29, 2025 at 2:37 PM
I'm now also looking for a postdoc with strong Bayesian background and interest in developing Bayesian cross-validation theory, methods and software. Apply by email with no specific deadline (see contact information at users.aalto.fi/~ave/).
Others, please share
Others, please share
Reposted by Magnus Johansson
New release of PowerLMM.js! Browser-based power analysis for longitudinal models with dropout.
Now includes:
- Power analysis summary report
- Reproducible & shareable configs (URL/JSON)
- Calculations validated against R
- Hypothesis region visualization
powerlmmjs.rpsychologist.com
Now includes:
- Power analysis summary report
- Reproducible & shareable configs (URL/JSON)
- Calculations validated against R
- Hypothesis region visualization
powerlmmjs.rpsychologist.com
October 28, 2025 at 2:02 PM
New release of PowerLMM.js! Browser-based power analysis for longitudinal models with dropout.
Now includes:
- Power analysis summary report
- Reproducible & shareable configs (URL/JSON)
- Calculations validated against R
- Hypothesis region visualization
powerlmmjs.rpsychologist.com
Now includes:
- Power analysis summary report
- Reproducible & shareable configs (URL/JSON)
- Calculations validated against R
- Hypothesis region visualization
powerlmmjs.rpsychologist.com
Reposted by Magnus Johansson
🎉 @rpsychologist.com 's PowerLMM.js is the online statistics application of the year 2025 🎉
powerlmmjs.rpsychologist.com
- Calculate power (etc) for multilevel models
- Examine effects of dropout and other important parameters
- Fast! (Instant results)
powerlmmjs.rpsychologist.com
- Calculate power (etc) for multilevel models
- Examine effects of dropout and other important parameters
- Fast! (Instant results)
October 28, 2025 at 2:37 PM
🎉 @rpsychologist.com 's PowerLMM.js is the online statistics application of the year 2025 🎉
powerlmmjs.rpsychologist.com
- Calculate power (etc) for multilevel models
- Examine effects of dropout and other important parameters
- Fast! (Instant results)
powerlmmjs.rpsychologist.com
- Calculate power (etc) for multilevel models
- Examine effects of dropout and other important parameters
- Fast! (Instant results)
Reposted by Magnus Johansson
in my post-academic era i have become extremely scathing of the way academia considers papers to the primary outcome of intellectual work, and refuses to give credit to academics who write software or build other tooling. in industry we very rarely read your papers; but we always use your software
October 28, 2025 at 2:15 AM
in my post-academic era i have become extremely scathing of the way academia considers papers to the primary outcome of intellectual work, and refuses to give credit to academics who write software or build other tooling. in industry we very rarely read your papers; but we always use your software
Reposted by Magnus Johansson
We wrote an article explaining why you shouldn't put several variables into a regression model and report which are statistically significant - even as exploratory research. bmjmedicine.bmj.com/content/4/1/.... How did we do?
October 27, 2025 at 5:39 PM
We wrote an article explaining why you shouldn't put several variables into a regression model and report which are statistically significant - even as exploratory research. bmjmedicine.bmj.com/content/4/1/.... How did we do?
I've done some more work on the relative measurement uncertainty, comparing `brms` posterior draws to "plausible values" in Rasch models, and some other reliability metrics. Estimating RMU from draws adds some variation, as shown in the figure.
pgmj.github.io/reliability....
#rstats #psychometrics
pgmj.github.io/reliability....
#rstats #psychometrics
October 24, 2025 at 4:49 PM
I've done some more work on the relative measurement uncertainty, comparing `brms` posterior draws to "plausible values" in Rasch models, and some other reliability metrics. Estimating RMU from draws adds some variation, as shown in the figure.
pgmj.github.io/reliability....
#rstats #psychometrics
pgmj.github.io/reliability....
#rstats #psychometrics
Reposted by Magnus Johansson
Anthony Biglan's "The Nurture Effect" shines a light on how we can intentionally design better societies. It's about building upstream prevention and fostering nurturing environments. What are your thoughts? snapt.io/CUHnJ #SocialScience #CommunityDevelopment #Prevention Image: Vectzeey
October 23, 2025 at 8:47 PM
Anthony Biglan's "The Nurture Effect" shines a light on how we can intentionally design better societies. It's about building upstream prevention and fostering nurturing environments. What are your thoughts? snapt.io/CUHnJ #SocialScience #CommunityDevelopment #Prevention Image: Vectzeey
Reposted by Magnus Johansson
Largest study of its kind shows AI assistants misrepresent news content 45% of the time – regardless of language or territory. www.bbc.co.uk/mediacentre/...
Largest study of its kind shows AI assistants misrepresent news content 45% of the time – regardless of language or territory
An intensive international study was coordinated by the European Broadcasting Union (EBU) and led by the BBC
www.bbc.co.uk
October 23, 2025 at 5:17 PM
Largest study of its kind shows AI assistants misrepresent news content 45% of the time – regardless of language or territory. www.bbc.co.uk/mediacentre/...
Reposted by Magnus Johansson
this tweet turns 10 today 🎂🥳
October 16, 2025 at 9:25 PM
this tweet turns 10 today 🎂🥳
Reposted by Magnus Johansson
Against Publishing: universonline.nl/nieuws/2025/...
Preprints are read, shared, and cited, yet still dismissed as incomplete until blessed by a publisher. I argue that the true measure of scholarship lies in open exchange, not in the industry’s gatekeeping of what counts as published.
Preprints are read, shared, and cited, yet still dismissed as incomplete until blessed by a publisher. I argue that the true measure of scholarship lies in open exchange, not in the industry’s gatekeeping of what counts as published.
October 14, 2025 at 9:16 AM
Against Publishing: universonline.nl/nieuws/2025/...
Preprints are read, shared, and cited, yet still dismissed as incomplete until blessed by a publisher. I argue that the true measure of scholarship lies in open exchange, not in the industry’s gatekeeping of what counts as published.
Preprints are read, shared, and cited, yet still dismissed as incomplete until blessed by a publisher. I argue that the true measure of scholarship lies in open exchange, not in the industry’s gatekeeping of what counts as published.
Very useful extension! I used an earlier version in this paper: pgmj.github.io/rasch_itemfit/
October 13, 2025 at 3:40 PM
Very useful extension! I used an earlier version in this paper: pgmj.github.io/rasch_itemfit/
Reposted by Magnus Johansson
I agree. #openscience combined with #opensource software is great!
This is what I find awesome (in the truest sense) about scientific development in the modern age. One group posts a new technique and within a few days it is implemented by others. #rstats is magic (and efficient)
This is really neat. I have borrowed the reliability() function to my `easyRasch` package, and use plausible values instead of fully Bayesian estimation to produce similar estimates/CIs, see code example below. RMU point estimates are similar to EAP reliability.
pgmj.github.io/easyRasch/re...
pgmj.github.io/easyRasch/re...
October 11, 2025 at 9:02 AM
I agree. #openscience combined with #opensource software is great!
This is really neat. I have borrowed the reliability() function to my `easyRasch` package, and use plausible values instead of fully Bayesian estimation to produce similar estimates/CIs, see code example below. RMU point estimates are similar to EAP reliability.
pgmj.github.io/easyRasch/re...
pgmj.github.io/easyRasch/re...
New preprint with @rogierk.bsky.social @paulbuerkner.com - we introduce "relative measurement uncertainty" - a reliability estimation method that's applicable across a broad class of Bayesian measurement models (e.g., generative-, computational- and item response theory-models osf.io/h54k8
OSF
osf.io
October 10, 2025 at 2:10 PM
This is really neat. I have borrowed the reliability() function to my `easyRasch` package, and use plausible values instead of fully Bayesian estimation to produce similar estimates/CIs, see code example below. RMU point estimates are similar to EAP reliability.
pgmj.github.io/easyRasch/re...
pgmj.github.io/easyRasch/re...
Reposted by Magnus Johansson
I really really really liked The Oatmeal’s take on AI here theoatmeal.com/comics/ai_art
A cartoonist's review of AI art - The Oatmeal
This is a comic about AI art.
theoatmeal.com
October 8, 2025 at 1:57 PM
I really really really liked The Oatmeal’s take on AI here theoatmeal.com/comics/ai_art
Reposted by Magnus Johansson
”AI isn't going to wake up, become superintelligent and turn you into paperclips – but rich people with AI investor psychosis are almost certainly going to make you much, much poorer.”
pluralistic.net/2025/09/27/e...
pluralistic.net/2025/09/27/e...
Pluralistic: The real (economic) AI apocalypse is nigh (27 Sep 2025) – Pluralistic: Daily links from Cory Doctorow
pluralistic.net
October 8, 2025 at 5:24 AM
”AI isn't going to wake up, become superintelligent and turn you into paperclips – but rich people with AI investor psychosis are almost certainly going to make you much, much poorer.”
pluralistic.net/2025/09/27/e...
pluralistic.net/2025/09/27/e...
Reposted by Magnus Johansson
#statstab #432 PsychOpen Gold
Thoughts: instead of submitting to greedy and unhelpful publishers, try this list of fully open and free journals in psychology.
#OpenScience #openaccess #apcs #goldaccess #pedagogy
psychopen.eu
Thoughts: instead of submitting to greedy and unhelpful publishers, try this list of fully open and free journals in psychology.
#OpenScience #openaccess #apcs #goldaccess #pedagogy
psychopen.eu
PsychOpen GOLD: Open Access Publishing
We are a Diamond Open Access platform for psychology research. Peer-reviewed, free-to-read journals with no publication fees, promoting open science.
psychopen.eu
October 7, 2025 at 7:22 PM
#statstab #432 PsychOpen Gold
Thoughts: instead of submitting to greedy and unhelpful publishers, try this list of fully open and free journals in psychology.
#OpenScience #openaccess #apcs #goldaccess #pedagogy
psychopen.eu
Thoughts: instead of submitting to greedy and unhelpful publishers, try this list of fully open and free journals in psychology.
#OpenScience #openaccess #apcs #goldaccess #pedagogy
psychopen.eu
Reposted by Magnus Johansson
Love this paper by Hinne doi.org/10.1177/2515... but curious why BMA isn't compatible with competing theories: "BMA is less useful when...each candidate model may represent a different theory of a physical process...the models are not a nuisance factor; they are the focus of the analysis." #statsky
A Conceptual Introduction to Bayesian Model Averaging - Max Hinne, Quentin F. Gronau, Don van den Bergh, Eric-Jan Wagenmakers, 2020
Many statistical scenarios initially involve several candidate models that describe the data-generating process. Analysis often proceeds by first selecting the ...
doi.org
October 5, 2025 at 7:35 AM
Love this paper by Hinne doi.org/10.1177/2515... but curious why BMA isn't compatible with competing theories: "BMA is less useful when...each candidate model may represent a different theory of a physical process...the models are not a nuisance factor; they are the focus of the analysis." #statsky