Magnus Johansson

@pgmj.bsky.social

2.4K followers 1.3K following 340 posts

PhD & lic. psychologist. Research specialist at Karolinska Institutet. R package for Rasch psychometrics: pgmj.github.io/easyRasch/
#openscience, #prevention, #psychometrics, #rstats, #photo

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Psychology 41%

Sociology 12%

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Magnus Johansson @pgmj.bsky.social · Mar 11

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

Detecting item misfit in Rasch models

pgmj.github.io

Reposted by Magnus Johansson

Jay Patel @infotainment.bsky.social · 3h

This is the avant-garde preprint service (hosted on AT Protocol) that I've been dreaming of.

If it's a small fraction of its vision down the road, I'd still be happy.

Check out Chive (docs.chive.pub/getting-star...).

- scholar owned
- open/community peer review
- semantic linking to terms

Reposted by Magnus Johansson

Tony Biglan President, Values to Action @tonybiglan.bsky.social · 5h

@bsky.app www.nytimes.com/2026/01/12/c...
another naked example of profits over people!

E.P.A. to Stop Considering Lives Saved When Setting Rules on Air Pollution

www.nytimes.com

Magnus Johansson @pgmj.bsky.social · 4d

I like them, but in this format (from smped.github.io/SimpleUpset/... )

Reposted by Martin Lang, Magnus Johansson, Patrick S. Forscher , and 3 more Martin Lang, Magnus Johansson, Patrick S. Forscher, Anthony J. Evans, Larry W. Hunter, Jill A. Jacobson

Eiko Fried @eikofried.bsky.social · 5d

After 5 years of data collection, our WARN-D machine learning competition to forecast depression onset is now LIVE! We hope many of you will participate—we have incredibly rich data.

If you share a single thing of my lab this year, please make it this competition.

eiko-fried.com/warn-d-machi...

WARN-D machine learning competition is live » Eiko Fried

If you share one single thing of our team in 2026—on social media or per email with your colleagues—please let it be this machine learning competition. It was half a decade of work to get here, especi...

eiko-fried.com

Reposted by Magnus Johansson, Paul Goldsmith-Pinkham

Vincent Arel-Bundock @vincentab.bsky.social · 6d

My poster got allocated prime real estate at the conference: High traffic, captive audience.

Magnus Johansson @pgmj.bsky.social · 10d

You are welcome! Glad to contribute something back. I've enjoyed reading many of your posts :)

Reposted by Magnus Johansson

Solomon Kurz @solomonkurz.bsky.social · 10d

The 1.3.0 version of my {brms} + {tidyverse} translation of Kruschke's "Doing Bayesian data analysis" is up!

solomon.quarto.pub/dbda2

#rstats

1/8

Doing Bayesian Data Analysis in brms and the tidyverse

solomon.quarto.pub

Magnus Johansson @pgmj.bsky.social · 10d

That is also recommended in this paper:

Balzer, L. B., & Westling, T. (2023). Invited Commentary: Demystifying Statistical Inference When Using Machine Learning in Causal Research. American Journal of Epidemiology, 192(9), 1545–1549. doi.org/10.1093/aje/...

Invited Commentary: Demystifying Statistical Inference When Using Machine Learning in Causal Research

Abstract. In this issue, Naimi et al. (Am J Epidemiol. 2023;192(9):1536–1544) discuss a critical topic in public health and beyond: obtaining valid statist

doi.org

Magnus Johansson @pgmj.bsky.social · 15d

Having to intermittently save backup copies (since MS OneDrive can't be trusted either) seems like something one should not have to do these days.

Magnus Johansson @pgmj.bsky.social · 15d

I'm writing a report with a deadline two days from now and Word keeps crashing 2-3 times a day. While the document is lengthy and has a lot of figures, it is just astounding that Microsoft haven't been able to make this program more stable after 40+ years of development.

Reposted by Linda J. Skitka, Olivier Corneille, Alexander Wuttke , and 4 more Linda J. Skitka, Olivier Corneille, Alexander Wuttke, Gernot Wagner, Jill A. Jacobson, Aleksandra Urman, Dietmar Fehr

Magnus Johansson @pgmj.bsky.social · 15d

"40 percent of MRI signals do not correspond to actual brain activity"; "Since tens of thousands of fMRI studies worldwide are based on this assumption, our results could lead to opposite interpretations in many of them.”
www.tum.de/en/news-and-...

40 percent of MRI signals misinterpreted

Interpretation of numerous MRI data may be incorrect: blood flow is not a reliable indicator of brain activity.

www.tum.de

Magnus Johansson @pgmj.bsky.social · 15d

Maybe, maybe not. bsky.app/profile/drda...

Alex Danvers @drdanvers.bsky.social · 16d

Yikes!
“Increased oxygen consumption – for instance in areas involved in calculation – did not coincide with the expected rise in blood flow. …analyses showed that these regions met their additional energy demand by extracting more oxygen from the unchanged blood supply.”

www.tum.de/en/news-and-...

40 percent of MRI signals misinterpreted

Interpretation of numerous MRI data may be incorrect: blood flow is not a reliable indicator of brain activity.

www.tum.de

Reposted by Magnus Johansson, Jill A. Jacobson

Alex Danvers @drdanvers.bsky.social · 16d

40 percent of MRI signals misinterpreted

Interpretation of numerous MRI data may be incorrect: blood flow is not a reliable indicator of brain activity.

www.tum.de

Magnus Johansson @pgmj.bsky.social · 21d

I'd ask the same question about any VAS rating scale.

Magnus Johansson @pgmj.bsky.social · 29d

Sounds like a proper winter. Here it only rains and +2-7 C temp. Dark and dreary :(

Magnus Johansson @pgmj.bsky.social · Dec 13

Linking to the actual research paper in the article would be helpful.

Reposted by Magnus Johansson

Solomon Kurz @solomonkurz.bsky.social · Dec 12

Another day, and another reference to these bangers. Contemporary causal inference has fundamentally changed the way I think about control variables and mediation analyses. These can show you why:

doi.org/10.1177/2515...
doi.org/10.1111/spc3...
doi.org/10.1177/2515...

Sage Journals: Discover world-class research

Subscription and open access journals from Sage, the world's leading independent academic publisher.

doi.org

Reposted by Dorothy Bishop, David Chester, Andrew K Przybylski , and 5 more Dorothy Bishop, David Chester, Andrew K Przybylski, Magnus Johansson, Patrick S. Forscher, Ariadne Vromen, Johannes Breuer, Jesper Wulff

Ian Hussey @ianhussey.mmmdata.io · Dec 12

Keeping this at hand in case I need to point to it and tap

Magnus Johansson @pgmj.bsky.social · Dec 12

Just realized I have an old gdrive folder with similar content, if it could be of interest: drive.google.com/drive/mobile...

Funktionell kontextualism - Google Drive

drive.google.com

Magnus Johansson @pgmj.bsky.social · Dec 12

Nice. This is also a great read: www.scribd.com/doc/29106580...

Gifford and Hayes - Functional Contextualism 1999 | PDF

Gifford and Hayes - Functional Contextualism 1999

www.scribd.com

Magnus Johansson @pgmj.bsky.social · Dec 11

Might this be applicable? journals.sagepub.com/doi/10.1177/...

These Are Not the Effects You Are Looking for: Causality and the Within-/Between-Persons Distinction in Longitudinal Data Analysis - Julia M. Rohrer, Kou Murayama, 2023

In psychological science, researchers often pay particular attention to the distinction between within- and between-persons relationships in longitudinal data a...

journals.sagepub.com

Reposted by Alexander Wuttke, Magnus Johansson

Ian Hussey @ianhussey.mmmdata.io · Dec 8

Today’s example of “self reported behaviour is a poor proxy of behaviour”: environmental behaviour

Cameron Brick @cameronbrick.bsky.social · Dec 8

Also, "research involving self-reports often leads to fundamentally different results than research focusing on actual behavior in incentivized settings"

2/3

Magnus Johansson @pgmj.bsky.social · Dec 8

Thanks, lots of interesting things discussed! Curious about why a zero-inflated or hurdle negbin was not used? ”We employ negative binomial regression models, which are well-suited to the outcome variable’s distribution — right-skewed with a large concentration of zero values.”