Joachim Baumann

At today’s lab reading group @carolin-holtermann.bsky.social presented ‘Fairness through Difference Awareness: Measuring Desired Group Discrimination in LLMs’ by @angelinawang.bsky.social et al. (2025).
Lots to think about how we evaluate fairness in language models!

#NLProc #fairness #LLMs

Also see more nuanced takes worth reading from @seanjwestwood.bsky.social (x.com/seanjwestwoo...) and @joshmccrain.bsky.social (bsky.app/profile/josh...) and @phe-lim.bsky.social (bsky.app/profile/phe-...)

The path forward: Survey panels and crowdsourcing platforms must invest in better panel curation and periodic quality verification.

Good to see that @joinprolific.bsky.social is already on it: bsky.app/profile/phe-...

✅ LLM instruction tuning works: tell a model to answer as a human, it will
❌ Silicon sampling still doesn't work: AI responses are plausible but don't accurately represent a real human population
❌ Bot detection fails: it's hard to design tasks that are easy for humans but difficult for LLMs

Now that the hype has cooled off, here's my take on AI-generated survey answers:
This is a real problem, but the paper's core insights aren't exactly news!
A thread with the most important summary... 🧵

Image: shows the LLM system prompt used

Another exhausting day in the lab… conducting very rigorous panettone analysis. Pandoro was evaluated too, because we believe in fair experimental design.

For our weekly reading group, @joachimbaumann.bsky.social presented the upcoming PNAS article "The potential existential threat of large language models to online survey research" by @
@seanjwestwood.bsky.social.

Auditing Google's AI Overviews and Featured Snippets: A Case Study on Baby Care and Pregnancy Google Search increasingly surfaces AI-generated content through features like AI Overviews (AIO) and Featured Snippets (FS), which users frequently rely on despite having no control over their presen...

Google AI overviews now reach over 2B users worldwide. But how reliable are they on high stakes topics - for instance, pregnancy and baby care?

We have a new paper - led by Desheng Hu, now accepted at @icwsm.bsky.social - exploring that and finding many issues

Preprint: arxiv.org/abs/2511.12920
🧵👇

Trying an experiment in good old-fashioned blogging about papers: dallascard.github.io/granular-mat...

Next Wednesday, we are very excited to have
@joachimbaumann.bsky.social, who will present co-authored work on "Large Language Model Hacking: Quantifying the Hidden Risks of Using LLMs for Text Annotation". Paper and information on how to join ⬇️

Can AI simulate human behavior? 🧠
The promise is revolutionary for science & policy. But there’s a huge "IF": Do these simulations actually reflect reality?
To find out, we introduce SimBench: The first large-scale benchmark for group-level social simulation. (1/9)

Cool paper by @eddieyang.bsky.social, confirming our LLM hacking findings (arxiv.org/abs/2509.08825):
✓ LLMs are brittle data annotators
✓ Downstream conclusions flip frequently: LLM hacking risk is real!
✓ Bias correction methods can help but have trade-offs
✓ Use human expert whenever possible

Looks interesting! We have been facing this exact issue - finding big inconsistencies across different LLMs rating the same text.

About last week’s internal hackathon 😏
Last week, we -- the (Amazing) Social Computing Group, held an internal hackathon to work on our informally called “Cultural Imperialism” project.

If you feel uneasy using LLMs for data annotation, you are right (if not, you should). It offers new chances for research that is difficult with traditional #NLP/#textasdata methods, but the risk of false conclusions is high!

Experiment + *evidence-based* mitigation strategies in this preprint 👇

The 94% LLM hacking success rate is achieved by annotating data with several model-prompt configs, then choosing the one that yields the desired result (70% if considering SOTA models only).
The 31-50% risk reflects well-intentioned researchers who just run one reasonable config w/o cherry-picking.

Thank you, Florian :) We use two methods, CDI and DSL. Both debias LLM annotations and reduce false positive conclusions to about 3-13%, on average, but at the cost of a much higher Type II risk (up to 92%). The human-only conclusions have a pretty low Type I risk as well, at a lower Type II risk.

Great question! Performance and LLM hacking risk are negatively correlated. So easy tasks do have lower risk. But even tasks with 96% F1 score showed up to 16% risk of wrong conclusions. Validation is important because high annotation performance doesn't guarantee correct conclusions.

We used 199 different prompts total: some from prior work, others based on human annotation guidelines, and some simple semantic paraphrases

Even when LLMs correctly identify significant effects, estimated effect sizes still deviate from true values by 40-77% (see Type M risk, Table 3 and Figure 3)

Thank you to the amazing @paul-rottger.bsky.social @aurman21.bsky.social @albertwendsjo.bsky.social @florplaza.bsky.social @jbgruber.bsky.social @dirkhovy.bsky.social for this fun collaboration!!

Why this matters: LLM hacking affects any field using AI for data analysis–not just computational social science!

Please check out our preprint, we'd be happy to receive your feedback!

#LLMHacking #SocialScience #ResearchIntegrity #Reproducibility #DataAnnotation #NLP #OpenScience #Statistics

The good news: we found solutions that help mitigate this:
✅ Larger, more capable models are safer (but no guarantee).
✅ Few human annotations beat many AI annotations.
✅ Testing several models and configurations on held-out data helps.
✅ Pre-registering AI choices can prevent cherry-picking.

- Researchers using SOTA models like GPT-4o face a 31-50% chance of false conclusions for plausible hypotheses.
- Risk peaks near significance thresholds (p=0.05), where 70% of "discoveries" may be false.
- Regression correction methods often don't work as they trade off Type I vs. Type II errors.

We tested 18 LLMs on 37 social science annotation tasks (13M labels, 1.4M regressions). By trying different models and prompts, you can make 94% of null results appear statistically significant–or flip findings completely 68% of the time.

Importantly this also concerns well-intentioned researchers!

We present our new preprint titled "Large Language Model Hacking: Quantifying the Hidden Risks of Using LLMs for Text Annotation". We quantify LLM hacking risk through systematic replication of 37 diverse computational social science annotation tasks. For these tasks, we use a combined set of 2,361 realistic hypotheses that researchers might test using these annotations. Then, we collect 13 million LLM annotations across plausible LLM configurations. These annotations feed into 1.4 million regressions testing the hypotheses. For a hypothesis with no true effect (ground truth $p > 0.05$), different LLM configurations yield conflicting conclusions. Checkmarks indicate correct statistical conclusions matching ground truth; crosses indicate LLM hacking -- incorrect conclusions due to annotation errors. Across all experiments, LLM hacking occurs in 31-50\% of cases even with highly capable models. Since minor configuration changes can flip scientific conclusions, from correct to incorrect, LLM hacking can be exploited to present anything as statistically significant.

🚨 New paper alert 🚨 Using LLMs as data annotators, you can produce any scientific result you want. We call this **LLM Hacking**.

Paper: arxiv.org/pdf/2509.08825

Not at this point, but the preprint should be ready soon

The @milanlp.bsky.social group is presenting 15 papers (+ a toturial) at this year's #ACL2025 , go check them out :)
bsky.app/profile/mila...

Shoutout to @tiancheng.bsky.social for yesterday's stellar presentation of our work benchmarking LLMs' ability to simulate group-level human behavior: bsky.app/profile/tian...

I'm at #ACL2025 this week:📍Find me at the FEVER workshop, *Thursday 11am* 📝 presenting: "I Just Can't RAG Enough" - our ongoing work with @aurman21.bsky.social & @rer.bsky.social & Anikó Hannák, showing that RAG does not solve LLM fact-checking limitations!

Breaking my social media silence because this news is too good not to share! 🎉
Just joined @milanlp.bsky.social as a Postdoc, working with the amazing @dirkhovy.bsky.social on large language models and computational social science!