Magnus Johansson

@pgmj.bsky.social

2529 Followers 1536 Following

PhD & lic. psychologist. Research specialist at Karolinska Institutet @ki.se . R packages for Rasch psychometrics: pgmj.github.io/easyRasch2 (also for jamovi) and easyRaschBayes. #openscience, #psychometrics, #rstats, #photo

Presentation slide with text:
A call to action
We need to collectively move the norms regarding cutoffs and methods
Please spread the word
Use this information when reviewing and writing papers
In your paper intros, mention limitations for old papers using old methods and/or fixed cutoffs.
Don’t assume that published papers are correct - most are likely to have errors of various severity
Editors could have a brief guideline/checklist for authors

Whitish ragdoll kitten.

Two plots side by side showing time in weeks on x axis and probability of returning to work on the y axis. The left hand plot shows the trajectory of two groups (self-efficacy improved or not improved), while the right hand plot shows the probability difference between the two groups.

A histogram with 10000 values using the mean+sd in the text, showing zero with a red line.

ggdist figure showing distribution of bias in estimation of item thresholds in a Rasch partial credit model, comparing three R packages, eRm, mirt, and TAM.

Large format 4x5” camera with 105mm lens, orange filter and a 6x12 roll film back.

Tindeq V-grip tool attached to a kettle bell for finger strength training.

Cat on an open book.

Tree with autumn colors from bright green to deep red.

Figure showing various levels of statistical power when the number of participants, effect size and dropout rate varies.