Magnus Johansson
@pgmj.bsky.social
2.3K followers 1.3K following 300 posts
PhD & lic. psychologist. Doing open science at Karolinska Institutet & RISE Research Institutes of Sweden. R package for Rasch psychometrics: pgmj.github.io/easyRasch/ #openscience, #prevention, #psychometrics, #rstats, #photo
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pgmj.bsky.social
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
systerfrida.se
”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: The real (economic) AI apocalypse is nigh (27 Sep 2025) – Pluralistic: Daily links from Cory Doctorow
pluralistic.net
Reposted by Magnus Johansson
mzloteanu.bsky.social
#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
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
Reposted by Magnus Johansson
rbly.bsky.social
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
Reposted by Magnus Johansson
adapalmer.bsky.social
Exceptional Doctorow piece on the solar rollout, why it's unstoppable, & why many old downsides of solar aren't factors anymore. The entire material mining needed 4 a global solar transition = only 17% of the fossil fuel mining we do every year! & then we're done! doctorow.medium.com/https-plural...
Decarbonization at a distance
A post-American century that runs on sunshine.
doctorow.medium.com
Reposted by Magnus Johansson
ianhussey.mmmdata.io
My article "Data is not available upon request" was published in Meta-Psychology. Very happy to see this out!
open.lnu.se/index.php/me...
LnuOpen | Meta-Psychology
open.lnu.se
pgmj.bsky.social
I'm sure there are ways it is brilliant, but my first methods check in EFA/CFA psychometric papers is always whether rule-of-thumb critical values are used to assess model fit. I don't think we should trust model fit interpretations using rule-of-thumb cutoffs in any paper.
Reposted by Magnus Johansson
matti.vuorre.com
100% this, especially with Wiley given their anti-preprint stance.
francescopoli.bsky.social
Why are we still sending our work to Wiley and other publishing companies so that they can profit from it? There's so many better options now, for example: psychopen.eu/journals/
pgmj.bsky.social
Interesting paper on how software could help analysts. ”Causal clarity in statistical software” (Korf et al., 2025). I like many of the ideas, such as clarifying estimand, using multiple estimators, and no output of coefficients for adjustment variables doi.org/10.1093/ije/... #stats #rstats
Causal clarity in statistical software
Imagine running a simple regression in any statistical software of choice—but this time, you only get a point estimate of the regression coefficient. There
doi.org
Reposted by Magnus Johansson
emilhvitfeldt.bsky.social
I'm exited to announce a new resource about making slides with quarto and revealjs. This book is the combination of all the work I have done in this area, reordered and polished up

There isn't a lot of new information yet, but this format allows me to add more easily

slidecrafting-book.com
#quarto
Screenshot of first page of slidecrafting-book.com website
Reposted by Magnus Johansson
annaalexandrova.bsky.social
I hope Melvin Bragg's retirement will not end In Our Times. He has a lovely voice and manner but it's the people he invites that hold the show. I'll take this chance to post a thread of some of the more memorable episodes for me. Starting with Schaffer, Worrall, and @michelamassimi.bsky.social
BBC Radio 4 - In Our Time, The Scientific Method
Melvyn Bragg and his guests discuss the Scientific Method.
www.bbc.co.uk
pgmj.bsky.social
Indeed, and since data is always collected within a known time-frame, there is also a known upper bound, which count models generally do not respect. The impact of ignoring the upper bound (and potential one-inflation) will of course depend on the distribution.
ajamesgreen.bsky.social
This is why I wrote a paper on count regression, and in general am a big proponent of generalised linear models. Almost nothing is 'normal'/gaussian. Days off sick are very obviously a count (whole numbers only, never below zero) doi.org/10.1080/2164...
pgmj.bsky.social
For instance, yesterday I read a paper with a table describing participants' sickness absence days with a mean of 71 and SD = 88. Generating a random (gaussian) sample using these values produces ~20% participants with less than zero sick days.
pgmj.bsky.social
Just to clear, it is not possible to have a negative number of sickness absence days, zero is the lower bound on this type of data.
pgmj.bsky.social
For instance, yesterday I read a paper with a table describing participants' sickness absence days with a mean of 71 and SD = 88. Generating a random (gaussian) sample using these values produces ~20% participants with less than zero sick days.
A histogram with 10000 values using the mean+sd in the text, showing zero with a red line.
pgmj.bsky.social
For those unfamiliar with `fivenumber()`, the five numbers are the median, minimum, maximum, and the lower and upper hinges. The hinges are the median values of the upper and lower halves (split by the median).
pgmj.bsky.social
My impression is that papers in psychology often seem to assume all variables are gaussian and well described by mean/SD as summary stats. Having actually looked at a lot of data distributions in psych has made me a proponent of Tukey’s `fivenumber()` summary statistics.
pgmj.bsky.social
I should add that describing reliability properties of a sample is of course a useful thing. But when doing psychometrics we also like to know the properties of the test/measure itself, to understand it's limitations and uses.
pgmj.bsky.social
Brilliant package name and sticker!
pgmj.bsky.social
Most point estimates of reliability have two main problems. One is that they typically describe properties of a sample, not a measure. Then they make it seem like reliability is a constant across the continuum measured, which is unlikely.
mzloteanu.bsky.social
#statstab #418 On Misconceptions and the Limited Usefulness of Ordinal Alpha

Thoughts: Ordinal α seemed cool. Then I read this paper. Takeaway: methods need good peer review and debate.

#ordinal #likert #cronbachalpha #reliability #methods

doi.org/10.1177/0013...
Sage Journals: Discover world-class research
Subscription and open access journals from Sage, the world's leading independent academic publisher.
doi.org