iiinova — where your digital self keeps evolving

Magnus Johansson @pgmj.bsky.social · 23/09/2026

Version 3.2.2 of my jamovi module for #Rasch #psychometrics is now available. It brings conditional reliability, a Reliable Change Index with exact critical values, and a new targeting figure. The module uses #rstats pkg easyRasch2 v1.3.1 and produces identical results. pgmj.github.io/easyRasch2/

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Magnus Johansson @pgmj.bsky.social · 20/09/2026

Makina 67 (orange filter) Rollei RPX400@800

Black and white photo of a sunlit oak tree.

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Magnus Johansson @pgmj.bsky.social · 16/09/2026

Screenshot text from www.sciencedirect.com/journal/clin...

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Magnus Johansson @pgmj.bsky.social · 10/08/2026

Helpful cat also likes the vertical mouse.

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Magnus Johansson @pgmj.bsky.social · 03/07/2026

Yes, the handwaving is problematic, especially for single-item analysis (of any ordinal scale). And when you find a scale (DERS) with these response distributions, it raises a lot of questions. My initial example post was also from this scale.

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Magnus Johansson @pgmj.bsky.social · 02/07/2026

Another example of how useful {geomtextpath} can be, imho. This is from the item category probability plot in my {easyRasch2} package. Most psychometric papers within the factor analytic tradition seem to disregard evaluating how the response scale works, which I find difficult to understand.

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Magnus Johansson @pgmj.bsky.social · 15/06/2026

To make it more accessible to use up-to-date psychometric methods, I have made a module for www.jamovi.org, which has a nice point-and-click user interface. 'easyRasch2jmv' can be installed from within jamovi. The updated module added helpful text output together with the analysis output.

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Magnus Johansson @pgmj.bsky.social · 15/06/2026

We really need a collective effort to leave rule-of-thumb cutoffs and incorrect methods behind us. I think a key aspect is to treat older psychometric validations with skepticism, both in paper intros and method sections. "Inaugural" papers are particularly important to scrutinize.

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

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Magnus Johansson @pgmj.bsky.social · 11/05/2026

New Jamovi module functionality to determine appropriate model fit cutoffs for confirmatory factor analysis now available in easyRasch2jmv v0.4.0. Install/update from Jamovi Library within the app. #rstats #psychometrics #stats #openscience

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Magnus Johansson @pgmj.bsky.social · 23/04/2026

You can also get traceplots for item category probabilities and targeting (person-item Wright map), and conditional item characteristic curves.

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Magnus Johansson @pgmj.bsky.social · 23/04/2026

I've made an R package for Bayesian Rasch #psychometrics with brms models, easyRaschBayes (on CRAN), implementing simple functions to create figures and tables with model fit metrics, etc. Attaching figures from conditional item infit, item-restscore with GK gamma, and the log-likelihood criterion.

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Magnus Johansson @pgmj.bsky.social · 08/01/2026

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

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Magnus Johansson @pgmj.bsky.social · 02/12/2025

geomtextpath can really help make a plot easier to interpret. Nice to avoid using a legend. #rstats #dataviz

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.

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Magnus Johansson @pgmj.bsky.social · 21/11/2025

More tinkering with relative measurement uncertainty proposed by @bignardi.bsky.social et al, using plausible values to estimate conditional reliability (inspired by @dmcneish.bsky.social) for Rasch models with WL estimation of latent scores. Code here: github.com/pgmj/easyRas...

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Magnus Johansson @pgmj.bsky.social · 24/10/2025

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

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Magnus Johansson @pgmj.bsky.social · 10/10/2025

The RelRep.R function "just works" with a dataframe with items as columns and produces pretty neat output for alpha or omega. Point estimate and CI for alpha is almost identical to RMU for my example with `eRm::raschdat1[,1:20]` data. github.com/melissagwolf...

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Magnus Johansson @pgmj.bsky.social · 22/09/2025

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.

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Magnus Johansson @pgmj.bsky.social · 15/08/2025

Grateful to have this view a few minutes walk from home.

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Magnus Johansson @pgmj.bsky.social · 07/08/2025

Inspired by a paper (linked) that added a response category to the PHQ-2 and GAD-2 screener questionnaires we did the same in Swedish with good results in a sample of 15-18 year olds. The uppermost categories performed worse, though (q25-26=GAD,27-28=PHQ). #psychometrics osf.io/preprints/ps...

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Magnus Johansson @pgmj.bsky.social · 04/08/2025

Reading the preface to "Thinking through statistics" and this section already made me like the book.

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Magnus Johansson @pgmj.bsky.social · 29/07/2025

Might be the perfect guitar string gauge? Seems ridiculous, but .005 inches thinner than the .011 I've used forever on my solid body seems really nice.

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Magnus Johansson @pgmj.bsky.social · 22/05/2025

...since it needs revising (ongoing) to incorporate correct information about critical values for GOF metrics: osf.io/preprints/os... We basically use the 4 criteria as presented by Kreiner (2007), who refers to Rosenbaum (1989).

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Magnus Johansson @pgmj.bsky.social · 29/04/2025

Really looking forward to this. It's been six years since his last book.

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Magnus Johansson @pgmj.bsky.social · 12/03/2025

Great to see conditional reliability and the "targeting" of test/sample discussed. I've incorporated a similar approach in a TIF curve figure in the `easyRasch` R package. Note that IRT/Rasch also provides information about the reliability of the test/questionnaire itself, independent of the sample.

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Magnus Johansson @pgmj.bsky.social · 15/01/2025

Such style and grace. Have one of those too

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Magnus Johansson @pgmj.bsky.social · 11/01/2025

Made with a Makina 67 a few years ago. Rollei Retro 400S overexposed a step and developed in Adox Silvermax 1+19. #filmphotography #blackandwhite #believeinfilm

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Magnus Johansson @pgmj.bsky.social · 28/12/2024

Sunset at 13.30 has some benefits.

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Magnus Johansson @pgmj.bsky.social · 25/12/2024

Stunning clouds, which my old phone struggles to reproduce.

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Magnus Johansson @pgmj.bsky.social · 21/09/2024

Colors and sunlight this time of year is just so nice.

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Magnus Johansson @pgmj.bsky.social · 04/09/2024

The TAM author does not seem very enthusiastic about that setting though

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Magnus Johansson @pgmj.bsky.social · 04/09/2024

I also added multicore processing and introduced a bug. Here are proper results, table and figure.

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Magnus Johansson @pgmj.bsky.social · 04/09/2024

I added `pairwise` and reran the same 250 datasets (9 items, 4 thresholds each, using PCM with 720 well-targeted simulated responses for each iteration). PAIR seems to perform worst. Summary table of absolute deviations from input parameters.

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Magnus Johansson @pgmj.bsky.social · 03/09/2024

I messed up earlier, assuming the output of tam.threshold() to be comparable to similar functions in other packages. But useful item thresholds were found in the tam() output object and I could rerun the simulation. Less bad for TAM, but still worse than eRm and mirt. #rasch #rstats #psychometrics

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.

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Magnus Johansson @pgmj.bsky.social · 21/07/2024

Berg ur arkivet. Utsikt från Ryfjället.

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Magnus Johansson @pgmj.bsky.social · 05/05/2024

Almost finished the first roll on my “new” 6x12 back today.

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Magnus Johansson @pgmj.bsky.social · 26/04/2024

Trying conditional formatting with the R `tinytable` package by @vincentab.bsky.social and was happy to see that `cell_spec()` styling works well (in addition to everything in the tutorial). #rstats

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Magnus Johansson @pgmj.bsky.social · 21/04/2024

Ser lite lovande ut från nästa söndag iaf.

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Magnus Johansson @pgmj.bsky.social · 20/04/2024

First shot with the Horseman 6x12 roll film back on my Linhof Technikardan 45 S. Seems like a solid piece of work. Looking forward to do some panorama landscape work with longer focal lengths.

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

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Magnus Johansson @pgmj.bsky.social · 01/04/2024

I’m running a simulation study comparing two R packages for Rasch Partial Credit Model estimation. Across datasets with 3-5 response categories, TAM (Marginal ML) shows increasingly biased estimates for outer categories, while eRm (Conditional ML) is consistent. #psychometrics

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Magnus Johansson @pgmj.bsky.social · 10/03/2024

Not much light or color today. But a nice tree by the lake.

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Magnus Johansson @pgmj.bsky.social · 07/03/2024

On this day a year ago. Haven’t seen much if any snow at all for several weeks now.

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Magnus Johansson @pgmj.bsky.social · 14/02/2024

Randomly occurring temporary weight increase…

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