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Guido Biele

@guidobiele.bsky.social

Bayesian stats, causal inference, child and youth mental health. https://gbiele.github.io/

140 Followers  |  276 Following  |  38 Posts  |  Joined: 25.09.2023  |  2.2078

Latest posts by guidobiele.bsky.social on Bluesky

wrote a bit fast, that's probably not an issue if one assumes the proportional odds assumtions holds and models the data accordingly, as done in the example.
If one relaxes the assumption and models category specific effects, things are probably different.

25.08.2025 15:34 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0

Very cool! I'm intrigued by the treatment of ordinal variables, and I have a question. Will this approach: avg_comparisons(mod_ord, variables = "partner", hypothesis = ~ I(sum(x * 1:5))) also give a good answer when the response-distribution is unbalanced, e.g. most people responded on level 1?

25.08.2025 15:25 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 2    πŸ“Œ 0
Identifying Bayesian Mixture Models

If you are not discouraged by now, here is a relevant paper: Bayesian Identification and Estimation of Growth Mixture
Models (Xiao, Rabe-Heskeseth & Skrondal, 2025) www.duo.uio.no/bitstream/ha...

13.08.2025 10:54 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0
Identifying Bayesian Mixture Models

The question is well motivated, but there will be stumbling blocks or walls one can run into:
- degenerate classes / label switching (betanalpha.github.io/assets/case_...)
- finding # of latent classes
- non-informative class membership probs

I think very clean data are needed to have a chance.

13.08.2025 10:50 β€” πŸ‘ 4    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0

No worries, das Deutsch ist nicht so gut, als dass man leicht Unterhaltungen auf Deutsch fΓΌhren kΓΆnnte πŸ˜€. (Bin weder verwandt noch verschwΓ€gert mit dem EigentΓΌmer...)

10.08.2025 13:39 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

I recommend this places: maps.app.goo.gl/H2QkoDjDbJr8...
The owner speaks some German πŸ˜€. More importantly, it's a friendly and quiet place with reasonably priced very good meals and nice outdoor seating in the backyard.

10.08.2025 09:46 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0

I think a "rich-get-richer" effect could be stronger if one does not provide additional info. But that would in my view also be bad practice. Asking an LLM to help with a review by using a RAG system with the relevant literature could well make the effect weaker.

01.08.2025 14:10 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

Genau fΓΌr diese Art von Text, der in erster Linie fΓΌr Verwaltungszwecke verfasst wird, sind m. E. LLMs nΓΌtzliche und effiziente Werkzeuge, bei denen, aus meiner Sicht, die Vorteile ggΓΌ den Nachteilen der Nutzung ΓΌberwiegen.

28.07.2025 09:01 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

Generally agree. An neat use of ordinal regressions is to use them as a semi-parametric model for weird (multimodal) VAS data. If one splits the original scale in bins, one can with some effort calculate marginal effects on the original scale, with resolution depending on # of bins.

28.07.2025 07:25 β€” πŸ‘ 0    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

Typos in the post are virtue signals, indicating that no LLM was used in its writing πŸ˜€

23.07.2025 16:16 β€” πŸ‘ 0    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

The last few days a couple of texts made the round here that equate using AI in the research process with doing bad research. I think these are 2 orthogonal things: Using AI can make research worse and it can make it better, depent on how it is used.

23.07.2025 16:12 β€” πŸ‘ 0    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0

I don't see how the post effectively criticises target population estimands. It shows that if you have a target population estimand in mind, but your study isn't designed to estimate it, you'll pay with a high variance of your estimate.

14.07.2025 16:00 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0

OTH, β€œOur analysis should take into account that children grow around 7.5 cm per year and rarely less than 1 cm or more than 15 cm per year.” sounds entirely reasonable and illustrates that priors often reflect not just subjective beliefs but objective information that can robustify inference.

02.07.2025 14:47 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

One reason for the lack of appreciation might be that Bayesian methods are often taught in a very abstract way, just as in the book at the start of the thread. Teaching the formula β€œposterior = prior Γ— likelihood” tends to focus attention on so-called subjective beliefs as priors.

02.07.2025 14:45 β€” πŸ‘ 0    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0

I agree that one can use Bayes for many reasons and that it is useful in relatively simple situations. However, my (admittedly limited) observation is that the ability to fit complex models attracts more people to Bayesian estimation than improved inference in simpler cases.

02.07.2025 12:49 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0

It works usually well if one uses t-tests or anovas to analyse simple experiments. But one shouldn't generalise from that to the goals/usefulness of Bayesian or Frequentist methods in general.

02.07.2025 07:26 β€” πŸ‘ 0    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

It seems to be a common misunderstanding that the goal of applied Bayesian inference is to let the prior influence the inference. I think a more common goal is to be able to reliably fit complex models that are hard/impossible with Frequentist methods.

02.07.2025 07:22 β€” πŸ‘ 18    πŸ” 1    πŸ’¬ 2    πŸ“Œ 0

Did they look at both parental income and education? In Norwegian data the association of child outcomes with parental education is clearly stronger than with parental income.

26.06.2025 15:43 β€” πŸ‘ 0    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0

To let LLMs produce less common and therefore likely also more creative text, one can always set the temperature parameter.
But there are trade offs. Less common might also be more likely wrong.

19.06.2025 15:47 β€” πŸ‘ 0    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
The Probability of Tiered Benefit: Partial Identification with Robust and Stable Inference We define the Probability of Tiered Benefit in scenarios with a binary exposure and an outcome that is either categorical with $K \geq 2$ ordered tiers or continuous partitioned by $K-1$ fixed thresho...

Sometimes psychologists collaborate with causal inference experts and use it for their research, here the probability of benefit or harm of ADHD medication for school outcomes: arxiv.org/abs/2502.10049
All math by @johandh2o.bsky.social

18.06.2025 15:24 β€” πŸ‘ 3    πŸ” 1    πŸ’¬ 1    πŸ“Œ 0
Transformers (how LLMs work) explained visually | DL5
YouTube video by 3Blue1Brown Transformers (how LLMs work) explained visually | DL5

Understanding the transformer architecture helps explain why LLMs are so powerfulβ€”and when they’re likely to fail.
The Andrej Karpathy video goes into less detail about transformers than would be helpful. Here's a quick and accessible intro from 3Blue1Brown. www.youtube.com/watch?v=wjZo...

18.06.2025 10:53 β€” πŸ‘ 0    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0
Post image

I believe large language models (LLMs) can be very useful and can be used to support learning effectively.
However, this plot from a recent study (www.nature.com/articles/s41...), which praises the impact of LLMs on learning outcomes, doesn't exactly inspire confidence.

05.06.2025 16:09 β€” πŸ‘ 6    πŸ” 1    πŸ’¬ 1    πŸ“Œ 0

Easily only for models with identity link function (also careful with treatment-interactions). Otherwise one might have to code up a model in e.g. Stan, omit priors on coefficients involving the treatment & put a prior on the marginal effect (calculated in the transformed parameters block).

02.06.2025 14:22 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0

The article talks about non-collapsibility, but doesn't seem to use the term. I think its a helpful term, because it puts a name to a key problem with OR, which is there even if the OR is not interpreted as a RR.

26.05.2025 14:17 β€” πŸ‘ 3    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

Links:
documents1.worldbank.org/curated/en/0...
assets-eu.researchsquare.com/files/rs-424...
arxiv.org/pdf/2409.090...
arxiv.org/pdf/2402.09809

21.05.2025 07:32 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

Would be great to have that on CRAN πŸ˜€

05.05.2025 14:45 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0

Ist natΓΌrlich auch mit Vorsicht zu geniessen. Eine wichtige SchwΓ€che ist, dass es alle Aussagen von Autoren unkritisch akzeptiert.

26.04.2025 11:45 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
Preview
Elicit: The AI Research Assistant Use AI to search, summarize, extract data from, and chat with over 125 million papers. Used by over 2 million researchers in academia and industry.

Genau, wenn schon, dann besser elicit.com :-)

26.04.2025 11:40 β€” πŸ‘ 4    πŸ” 1    πŸ’¬ 1    πŸ“Œ 0

Anyhow, I am sympathetic to focusing on selection bias, because I think quasi-experimental designs, which are often possible only in selected samples, focus so much on internal validity, that it easy to overlook that they might exchange confounding bias with selection bias.

18.04.2025 20:46 β€” πŸ‘ 3    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

Using missingnes graphs provide an additional way to define internal and external validity: violations of internal validity are due to backdoor paths that do not involve missingness indicator nodes (or their children) and violations of external validity involve those. (Just made this up ...)

18.04.2025 20:42 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 2    πŸ“Œ 0

@guidobiele is following 20 prominent accounts