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Giacomo Bignardi

@bignardi.bsky.social
578 followers 1.2K following 106 posts

Research Associate at the Social, Genetic & Developmental Psychiatry Centre, Kings College London. Interests: developmental psychology, data science, coffee. www.bignardi.co.uk

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Reposted by Giacomo Bignardi
ACAMH - Association for Child and Adolescent Mental Health @acamh.bsky.social · 24/07/2026
Family research in child and adolescent mental health has often been framed as if influence runs mainly from adults to children. In this #OpenAccess JCPP Advances Editorial, @eivindy.bsky.social comments on when children also shape the family environment. bit.ly/4f3FjyS
bit.ly
JCPP Advances | ACAMH Child Development Journal | Wiley Online Library
Family research in child and adolescent mental health has often been framed as if influence runs mainly from adults to children. Bjørndal et al. provide a timely corrective. Using longitudinal networ...
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Shawn Rhoads @shawnrhoadsphd.com · 13/07/2026
1/ I am thrilled to begin sharing the latest release of pyEM, a Python package I built for fitting cognitive computational models to behavioral data using hierarchical expectation maximization (EM) with maximum a posteriori estimation (MAP). github.com/shawnrhoads/...
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ACAMH - Association for Child and Adolescent Mental Health @acamh.bsky.social · 08/06/2026
Interested in exploring the intergenerational consequences of #racism? On 9 June 2026, ACAMH’s #ACEs SIG will hold a brilliant webinar on this very topic. In this Q&A, we caught up with the presenter – Dr. Yasmin Ahmadzadeh – about her research, and her hopes for the event. bit.ly/3PgufW2
bit.ly
Meet the expert: Intergenerational consequences of racism, with Dr. Yasmin Ahmadzadeh
On 9 June 2026, ACAMH’s Adverse Childhood Experiences (ACEs) Special Interest Group will hold its next meeting, Intergenerational Consequences of Racism. We caught up with the presenter - Dr. Yasmin A...
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Peter Tennant @pwgtennant.bsky.social · 12/05/2026
Scientists should be judged not just on their research, but the claims they make. Quitting smoking is one of the most powerful ways you can improve your health. Visiting a museum can never come close. Such a claim should require extraordinary evidence. This study is anything but. 18/18 🧵
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Michel Nivard @michelnivard.bsky.social · 28/04/2026
BGA needs people to communicate if their not going to back out/cancel last minute, or will only be present on 1/2 days, so they can allocate spots to our colleagues and friends who otherwise currently cannot attend due to venue capacity.
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Durham Institute for Medical Humanities @durhamimh.bsky.social · 23/04/2026
🚨 Call for Abstracts: The New Measurement Heretics We welcome proposals from researchers in the philosophy, history, sociology, and anthropology of measurement who would like to address themes around formal & informal measurement concepts ⚖️ Find out more 👇 medhumsplatform.org/call-for-abs...
medhumsplatform.org
Call for Abstracts: The New Measurement Heretics
We invite proposals from researchers in the philosophy, history, sociology and anthropology of measurement for a new edited collection. Deadline 15 June 2026.
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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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Nicholas Judd @njudd.com · 01/04/2026
Job ad: Postdoc to work with me & @rogierk.bsky.social at the Donders on lifespan development questions from Sept onward! Profile: independent, good quant skills, interested in theory-driven work Please share widely www.careersatradboudumc.com/vacancies/po... #Postdoc #AcademicJobs
careersatradboudumc.com
Vacancy — Postdoctoral researcher cognitive development
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Mark Rubin @markrubin.bsky.social · 17/03/2026
"There are signs that the Bayes Factor is increasingly taking on a role analogous to that of the p-value, serving as a device for the automation of decisions rather than as a tool for substantive inference." Excellent new preprint by Carol Ting on the rise of NHST. #Methodology #stats
arxiv.org
The Rise of Null Hypothesis Significance Testing (NHST): Institutional Massification and the Emergence of a Procedural Epistemology
It has long been a puzzle why, despite sustained reform efforts, many applied scientific fields remain dominated by Null Hypothesis Significance Testing (NHST), a framework that dichotomizes study res...
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Riccardo Fusaroli @fusaroli.eurosky.social · 04/02/2026
as I'm revising my course materials, I keep stumbling upon cool @mc-stan.org developments. Current favorites: 1. your model has funnels and you exhausted reparametrization ideas: metric = "dense_e" makes your HMC learn about covariance btw parameters. Sloooow, but effective! 1/
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Giacomo Bignardi @bignardi.bsky.social · 28/01/2026
Worth noting this approach works with python/jupyter aswell, and across windows/linux/macos. Also RAM prices will be crazy in 2026 due to AI, so prices will change!
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Giacomo Bignardi @bignardi.bsky.social · 28/01/2026
But you can also buy a windows/linux desktop or mini PC with lots of RAM for far less money, if you don't mind slightly worse CPU performance. The differences are even bigger if you need 128GB of RAM....
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Giacomo Bignardi @bignardi.bsky.social · 28/01/2026
Apple users who need 64GB of RAM will need to shell out either £3,879 for a MacBook 16 Pro or £1,839 for a Mac mini. Therefore, you could get both a 64GB mini and a basic MacBook Air (£900) for much less - and you'll only lose £900 when you leave your laptop on the tube.
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Giacomo Bignardi @bignardi.bsky.social · 28/01/2026
If you already have a gaming computer at home, with Docker + Tailscale, you can work from it remotely pretty seamlessly. Alternatively, if you only occasionally need more computer power, you can rent a server (running Docker) from your university or a private company (e.g., www.hetzner.com/cloud).
hetzner.com
Flexible Cloud Hosting Services und VPS Server
Hetzner Cloud Hosting Services ✓ VPS Server und Block Storage ✓ günstige Preise ✓ in Deutschland, Finland, USA und Singapur
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Giacomo Bignardi @bignardi.bsky.social · 28/01/2026
For illustrative purposes, I've installed tailscale on my desktop and phone. On my phone, I simply replace the localhost part of the web address with the tailscale ip address of my desktop, and bingo, I can access RStudio server on another device - and it works largely the same.
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Giacomo Bignardi @bignardi.bsky.social · 28/01/2026
A nice thing about Docker (though this isn't exclusive to Docker) is that it runs RStudio Server, which we access via a web browser. By default, we can only access it on our own computer, but we can also access it from other computers via a secure, encrypted connection using the free app Tailscale.
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Giacomo Bignardi @bignardi.bsky.social · 28/01/2026
Most of us work partly from home, so we need to work in different locations. For most, this means buying a laptop. However, if you work with large datasets and do complex analyses, you may need a higher-spec laptop with more RAM, which can cost 2-3x as much as the basic-spec version.
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Giacomo Bignardi @bignardi.bsky.social · 28/01/2026
Hot take: one of the main benefits of running data analyses in 🐬 Docker 🐬 isn't reproducibility, but saving yourself (or your lab) hundreds or thousands of pounds in computer costs*. Here's how... #datascience #docker #rstudio #python *for a very niche set of people
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Giacomo Bignardi @bignardi.bsky.social · 22/01/2026
video making very strong (& problematic) claims about the supposed damaging effects of screen time on children's education & cognition is trending on youtube (from the US senate committee)... www.youtube.com/watch?v=Fd-_...
youtube.com
Doctor on How Screen Time Hurts Kids' Cognitive Development
YouTube video by C-SPAN
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Giacomo Bignardi @bignardi.bsky.social · 22/01/2026
...claims such as: "Gen Z is the first population to cognitively underperform us on every measure", "Once countries widely adopt digital technologies in school, performance goes down wildly.", "We have evolved biologically to learn from other human beings, not from screens."
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Giacomo Bignardi @bignardi.bsky.social · 22/01/2026
video making very strong (& problematic) claims about the supposed damaging effects of screen time on children's education & cognition is trending on youtube (from the US senate committee)... www.youtube.com/watch?v=Fd-_...
youtube.com
Doctor on How Screen Time Hurts Kids' Cognitive Development
YouTube video by C-SPAN
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Michael "Shapes Dude" Betancourt @betanalpha.bsky.social · 21/01/2026
On Tues, February 17th I'll be giving a talk and short workshop on (narratively) generative modeling for Princeton's psychology department, psychology.princeton.edu/news-events/.... The talk (and maybe the workshop) will be live-streamed for those interested in attending remotely.
psychology.princeton.edu
Michael Betancourt - Chief Research Scientist, Symplectomorphic, LLC
Generative ModelingOver the last few years the term "generative modeling" has become increasingly popular.  The precise definition of the term, however, tends to be vague and often inconsistent across...
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rogier kievit @rogierk.bsky.social · 18/12/2025
I've used Lavaan almost every (work)day for 15 years, but this open source labour of love has never received proper institutional support. I'm delighted to be a small part of an 1.5M OpenScienceNL award, led by Jorgensen, to completely revamp and futureproof Lavaan www.openscience.nl/en/news/45-p...
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Giacomo Bignardi @bignardi.bsky.social · 09/12/2025
For those who have recieved non taxable phd stipends and have been in employment directly before or after, you may have overpaid your student loan due to the sneeky way it's collected...
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Giacomo Bignardi @bignardi.bsky.social · 09/12/2025
Wow if you have a UK student loan this is definitely worth checking, Xmas is on @martinlewis.moneysavingexpert.com again this year 🎄🎄https://www.moneysavingexpert.com/students/student-loan-overpayment-refund
moneysavingexpert.com
Student loan overpayments
This MoneySavingExpert guide can help you check if you've overpaid your student loan and reclaim the cash if so. 10,000s overpay their student loans – have you?
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Sara De Felice @saradefelice.bsky.social · 01/12/2025
In 2021 we reported that live learning outperformed recorded learning. In a new preregistered analysis, my first senior-author paper led by Stan de Visser (pre-print), we find that this benefit does not increase with interactivity. The potential to interact may be enough to boost learning. A thread:
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Payam Piray @payampiray.bsky.social · 17/11/2025
Happy to share my new paper published in @nathumbehav.nature.com: A critical look at statistical power in computational modeling studies, particularly those based on model selection. www.nature.com/articles/s41...
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Giacomo Bignardi @bignardi.bsky.social · 07/11/2025
Dont forget the true score isnt the actual "true" score, but the expected score.
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Giacomo Bignardi @bignardi.bsky.social · 29/10/2025
Link doesn't work for me sadly! :( Says bad gateway error?
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Dan Lewer @danlewer.bsky.social · 27/10/2025
We wrote an article explaining why you shouldn't put several variables into a regression model and report which are statistically significant - even as exploratory research. bmjmedicine.bmj.com/content/4/1/.... How did we do?
A "methods primer" article in the journal "BMJ Medicine", titled "Factors associated with: problems of using exploratory multivariable regression to identify causal risk factors"
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Giacomo Bignardi @bignardi.bsky.social · 20/10/2025
Interesting, thanks! I need to read up on this again as I don't remember all the different ICCs. Cool that it seems to match up with this formula!
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Giacomo Bignardi @bignardi.bsky.social · 20/10/2025
... which would converge to 1 as the number of raters increases? I assume with inter-rater reliability, researchers are interested in something like how well a single rater's ratings of the items match the "true" rating, which is quite different, and necessitates a different approach?
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Giacomo Bignardi @bignardi.bsky.social · 20/10/2025
Hmmm - I haven't really thought about inter-rater reliability since 2016 - so I'm not sure how RMU would map onto existing metrics yet. Thinking aloud: applying RMU to the item intercepts gives the reliability of the model's item estimates when combining all information across all raters...
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Prof Sarah-Jayne Blakemore @sjblakemore.bsky.social · 20/10/2025
New paper by brilliant final yer PhD student Blanca Piera Pi-Sunyer and colleagues, including 3 undergraduate students (Evans, Ratcliffe, Janaarthanan) 🤩 The Relationship between Perceived Friendship Quality and Self-Judgements in Adolescent Girls from London journals.sagepub.com/doi/epub/10....
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Gates Cambridge @gatescambridge.bsky.social · 31/01/2025
Blanca Piera Pi-Sunyer on how to make the world a better place for young people, the cumulative impact of adversity & how to mitigate it in the Gates Cambridge podcast, So, now what? - @cambridgeuni.bsky.social
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Giacomo Bignardi @bignardi.bsky.social · 17/10/2025
Could you share the models/code your using? Do you have estimates for subjects that you plug into the function?
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Giacomo Bignardi @bignardi.bsky.social · 10/10/2025
Neat! I have brms code for replicating (and going beyond) alpha too incase its useful: www.bignardi.co.uk/8_bayes_reli...
bignardi.co.uk
Estimating Mean Score Reliability with RMU
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Giacomo Bignardi @bignardi.bsky.social · 10/10/2025
Hmm, interesting, I've had this on my reading list but have not read it yet, the intro is so clear and great! I disagree that reliability implies equal precision across scores, but it seems like an interesting way of going beyond reliability...
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Giacomo Bignardi @bignardi.bsky.social · 10/10/2025
Good point, would be interesting to try (and also force myself to learn generalizability theory in more detail)!
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Giacomo Bignardi @bignardi.bsky.social · 10/10/2025
Helping a PhD student with SDT models was actually the original inspiration for this side project! I have example code applying the method to a SDT model below (actually borrowing code from @matti.vuorre.com's helpful blog on this) ->
bignardi.co.uk
Tutorial: Calculating RMU reliability for a go/no-go task
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Giacomo Bignardi @bignardi.bsky.social · 10/10/2025
Ah i misunderstood, no introduction rewrite needed yet then 😅. Good to know it gives similar results to the other approaches!
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Giacomo Bignardi @bignardi.bsky.social · 10/10/2025
Exciting! Just to check - can you get confidence intervals from PSI & EAP too?
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Magnus Johansson @pgmj.bsky.social · 10/10/2025
This is really neat. I have borrowed the reliability() function to my `easyRasch` package, and use plausible values instead of fully Bayesian estimation to produce similar estimates/CIs, see code example below. RMU point estimates are similar to EAP reliability. pgmj.github.io/easyRasch/re...
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Giacomo Bignardi @bignardi.bsky.social · 08/10/2025
I've added a new example to our paper's repo, demonstrating how our reliability method replicates Cronbach's alpha for a simple model, but also how our method can account for: (i) binary data, (ii) varying numbers of items per pps, & (iii) improvement over trials www.bignardi.co.uk/8_bayes_reli...
bignardi.co.uk
Estimating Mean Score Reliability with RMU
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Giacomo Bignardi @bignardi.bsky.social · 01/10/2025
Thanks Edwin! I only learned from the best 😜
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Giacomo Bignardi @bignardi.bsky.social · 01/10/2025
Great! Sorry just saw this before my replies :)
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Giacomo Bignardi @bignardi.bsky.social · 01/10/2025
I think both methods should converge to the same answer as the number of draws -> ∞. I think your approach is 1-V_w/V whereas empirical reliability is defined as v_a/(v_a+v_w) - but it should be the same as draws -> ∞. Pic from onlinelibrary.wiley.com/doi/10.1002/...
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Giacomo Bignardi @bignardi.bsky.social · 01/10/2025
Hi Ruben - i had the same thought - and it wasn't easy finding the reference in an old IRT manual! In your post, do you divide the variance of subjects' posterior means by the total variance in MCMC draws across subjects? The best description of ER is in here by Phil Chalmers tinyurl.com/4f3vv5e8
tinyurl.com
Difference between empirical and marginal reliability of an IRT model
I am using the mirt library in R to fit an instrument (binary responses) comprising two dimensions. In the mirt documentation are mentioned two types of reliability. I would like to ask what is the
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Giacomo Bignardi @bignardi.bsky.social · 01/10/2025
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Giacomo Bignardi @bignardi.bsky.social · 01/10/2025
Any (ideally helpful) comments/feedback/critique welcome! Email at: bignardig@outlook.com
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