Kristoffer Magnusson

11 Dec 2024

Introducing PowerLMM.js! A new tool for power analysis of longitudinal linear mixed-effects models (LMMs) – with support for missing data, plus non-inferiority and equivalence tests. powerlmmjs.rpsychologist.com Would really appreciate your feedback as I refine this app! Details below 🧵👇

Asked an LLM to briefly summarize a 600+ post datamethods thread, as I have better things to do. Didn't expect it to return a synopsis for a stats Kammerspiel.

Kristoffer Magnusson reposted

Marcus Crede

@marcuscrede.bsky.social

This is just the most amazing teaching tool ever!! Thank you Kristoffer.

Kristoffer Magnusson@rpsychologist.com

Understanding Maximum Likelihood Estimation, now in 3D!: rpsychologist.com/likelihood #dataviz #stats #rstats

Understanding Maximum Likelihood Estimation, now in 3D!: rpsychologist.com/likelihood #dataviz #stats #rstats

A meme thread on how I feel every time I use ZIB/ZOIB models. Feel free to add your own

A meme thread on how I feel every time I use ZIB/ZOIB models. Feel free to add your own

@laurenforrest.bsky.social

Kristoffer Magnusson reposted

Magnus Johansson

@pgmj.bsky.social

Our commentary "A Revolution in Search of an Estimand: On the Idionomic Proposal of Hayes et al. (2026)" is now available as a preprint: osf.io/preprints/ps... With @rpsychologist.com, @matti.vuorre.com, and Nils Hentati Isacsson.

osf.ioOSF

Magnus Johansson@pgmj.bsky.social

Interesting timing. I just noticed this paper: Hayes, S. C., Ciarrochi, J., Sahdra, B. K., Hofmann, S. G., Ong, C. W., & Hernández, C. (2026). One size fits none: A call for an idionomic revolution. Clinical Psychology Review, 129, 102800. doi.org/10.1016/j.cp...

doi.orgRedirecting

Kristoffer Magnusson reposted

Lauren Forrest

25 June

This blog post is a master class in (1) communicating a message so few articles (and analysts 😬) seem to fully understand/engage with and (2) the power of good data viz. Such a good and worthwhile read!

Kristoffer Magnusson@rpsychologist.com

New interactive blog! "Why Adjusted Regression Coefficients Are Less Descriptive Than They Look" rpsychologist.com/descriptive-...

25 June

New interactive blog! "Why Adjusted Regression Coefficients Are Less Descriptive Than They Look" rpsychologist.com/descriptive-...

25 June

Trying out Svelte for the first time here btw, really like it so far. Not sure why I didn't switch years ago.

Kristoffer Magnusson reposted

Magnus Johansson

@pgmj.bsky.social

23 Apr

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.

16 Apr

No one:   Absolutely no one: Billion-dollar publisher in 2026: “We published the wrong version so our only option is to issue a retraction under your name”

malus.shMALUS - Clean Room as a Service | Liberation from Open Source Attribution

25 Mar

We are not ready for the next generation of research misconduct. "Our proprietary AI robots independently recreate any open source project from scratch. The result? Legally distinct code with corporate-friendly licensing. No attribution. No copyleft." malus.sh

25 Mar

I hope this is satire, but considering everything we're seeing in research, this feels more like an ominous preview

If only...

Methodologists' theoretical papers: "you MUST do X or your estimates are meaningless." Methodologists' empirical papers: [does not do X]

10 Mar

Someone must've done a systematic review on whether methodologists follow their own advice?

6 Mar

Love methods papers where the authors cover an estimator’s properties in painstaking detail, then add a footnote: “We assume X, Y, Z, which are unrealistic, but relaxing them is too complex” Thanks. I suppose it’s up to us applied researchers to deal with those gaps then?

6 Mar

Julia M. Rohrer@dingdingpeng.the100.ci

Find someone who believes in you like researchers believe in pre-post differences as valid treatment effect estimates.

22 Feb

Opened Bluesky for some USA vs Canada hockey banter. Everyone’s discussing R pipes. 😑

28 Jan

Yes, archive OCI (Open Container Initiative) images for each project. Then we can simply docker / podman pull & run, without installing and fixing broken system or R package deps. This is much more future-proof and convenient than any R-only solution

Matti Vuorre@matti.vuorre.com

Don't get me started on targets/drake. Make it easy for others to use your code please.

28 Jan

No, everyone should not learn how to run their own Kubernetes cluster on arch. This should be handled centrally by the university when projects are archived.

Just added to PowerLMM.js v0.3: Interactive power contour plots! Visualize how statistical power changes across parameter combinations. powerlmmjs.rpsychologist.com?view=contour

10 Nov 2025

Fun fact about LMMs: when you have missing data, power also depends on the correlation between intercepts and slopes. In the clip, I’m varying the amount of random slope variance.

Kristoffer Magnusson reposted

Just added to PowerLMM.js v0.3: Interactive power contour plots! Visualize how statistical power changes across parameter combinations. powerlmmjs.rpsychologist.com?view=contour

Just added to PowerLMM.js v0.3: Interactive power contour plots! Visualize how statistical power changes across parameter combinations. powerlmmjs.rpsychologist.com?view=contour

Try it out and let me know what you think, it is still a bit experimental

30 Oct 2025

Wasn't that happy with how performance crashed as time points grew, so I dusted off some linear algebra to optimize the calculations. Benchmark showed a ~1Mx speedup using new implementation (with 100 time points) 😅

Kristoffer Magnusson@rpsychologist.com

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

Kristoffer Magnusson reposted

Matti Vuorre

@matti.vuorre.com

🎉 @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)

Kristoffer Magnusson reposted

Dan Quintana

@dsquintana.bsky.social

Who’s gonna pay @rpsychologist.com to make a mega tool converting all g*power analysis types to an interpretable web tool like this?

Kristoffer Magnusson@rpsychologist.com

Calculations have been validated against R. Validation notes: github.com/rpsychologis...

Plus: - New welcome screen - Guided help tour - View correlation matrix as a heat map - and other UI improvements ☕

Power analysis summary report, that can be printed or saved as a PDF

Share your analysis as a URL, or store it as a JSON file. For example: powerlmmjs.rpsychologist.com?n1=13&time_e...

Hypothesis region visualization. Interactive display of the chosen null and alternative hypothesis.

6 June 2025

Turns out proportions aren't collapsible after all. Take that, OR haters. "Globally, approximately 3.3% of the population reports using AAS, with prevalence rates of 6.4% among men [2] and 4% among women [3]."

youtube.comDigital media and its impact on children and adolescents – livestreamed Nordic and EU expert meetingYouTube video by Folkhälsomyndigheten

5 June 2025

I watched this so you don’t have to. A couple of highlights: ”I sometimes say that 'screen use', when putting that into statistical models, it’s sort of like looking at 'car use' when trying to find out why injuries are happening from car accidents” 🇳🇴 www.youtube.com/live/XKo6oUY...

youtube.comDigital media and its impact on children and adolescents – livestreamed Nordic and EU expert meetingYouTube video by Folkhälsomyndigheten

5 June 2025

Daniel Kardefelt-Winther presenting new analyses that covers nearly 39,000 children from 39 countries www.youtube.com/live/XKo6oUY... Spoiler alert: Screen time alone was weakly and inconsistently associated with mental health indicators

youtube.com2025 CAUSALab Methods Series with Jeremy LabrecqueYouTube video by CAUSALab at Harvard T.H. Chan

26 May 2025

Great talk by @jeremylabrecque.bsky.social "Before and after causal inference: recognizing causal questions and answering them when assumptions are violated" www.youtube.com/watch?v=9B-X...

26 May 2025

"The authors are the ones that are familiar with the data, that are experts ... they’re the ones that should be convincing us. They should be using all these extra methods like bias analyses and inputting their expert knowledge to convince us that the real answer is somewhere in this range"

23 May 2025

Not sure where to start with this one. Internet gaming addiction… is a risk factor for internet gaming disorder

23 May 2025

Honestly, with how fuzzy these construcs are I wouldn’t be surprised if there's no association

19 May 2025

Regarding the expert consensus on smartphone use: let’s not forget that the related “behavioral addiction” gaming disorder, is essentially a copy-paste job. Below is a visual comparison of the ICD-11 criteria for gaming and gambling disorder—essentially a substitution of terms.

19 May 2025

The only substantive change is replacing “financial losses” with “poor scholastic performance”. Gaming and gambling are not structurally or psychologically similar enough to justify this, and it raises serious concerns about construct validity and "expert consensus"