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Reposted by Chaitanya Malaviya

Ai2 @ai2.bsky.social · Aug 18

LLMs power research, decision‑making, and exploration—but most benchmarks don’t test how well they stitch together evidence across dozens (or hundreds) of sources. Meet MoNaCo, our new eval for question-answering cross‑source reasoning. 👇

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Chaitanya Malaviya @cmalaviya.bsky.social · Jul 30

People at #ACL2025, come drop by our poster today & chat with me about how context matters for reliable language model evaluations!

Jul 30, 11:00-12:30 at Hall 4X, board 424.

Chaitanya Malaviya @cmalaviya.bsky.social · Nov 13

Excited to share ✨ Contextualized Evaluations ✨!

Benchmarks like Chatbot Arena contain underspecified queries, which can lead to arbitrary eval judgments. What happens if we provide evaluators with context (e.g who's the user, what's their intent) when judging LM outputs? 🧵↓

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Reposted by Chaitanya Malaviya

Kyle Lo @ COLM 2025 🍁 @kylelo.bsky.social · Jul 22

issues w preference LM benchmarks:

🐡data contains cases where the "bad" response is just as good as chosen one
🐟model rankings can feel off (claude ranks lower than expected)

led by @cmalaviya.bsky.social, we study underspecified queries & detrimental effect on model evals; accepted to TACL 2025

Ai2 @ai2.bsky.social · Jul 22

In our new paper, “Contextualized Evaluations: Judging Language Model Responses to Underspecified Queries,” we find that adding just a bit of missing context can reorder model leaderboards—and surface hidden biases. 🧵👇

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Chaitanya Malaviya @cmalaviya.bsky.social · Jul 22

Context is an overlooked aspect of language model evaluations. Check out how to incorporate context into evaluations in our TACL paper, how it changes evaluation conclusions and makes evaluation more reliable!

Ai2 @ai2.bsky.social · Jul 22

In our new paper, “Contextualized Evaluations: Judging Language Model Responses to Underspecified Queries,” we find that adding just a bit of missing context can reorder model leaderboards—and surface hidden biases. 🧵👇

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Chaitanya Malaviya @cmalaviya.bsky.social · Jun 6

Check out our paper and counterfactual data below! 👇
• Paper: arxiv.org/abs/2506.05339
• Data: huggingface.co/datasets/abh...
• Code: github.com/anirudhb123/...

Flattery, Fluff, and Fog: Diagnosing and Mitigating Idiosyncratic Biases in Preference Models

Language models serve as proxies for human preference judgements in alignment and evaluation, yet they exhibit systematic miscalibration, prioritizing superficial patterns over substantive qualities. ...

arxiv.org

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Chaitanya Malaviya @cmalaviya.bsky.social · Jun 6

Our findings suggest that targeted debiasing using counterfactuals can help build more reliable preference models, a key step for both LLM alignment and evaluation.

Work led by Anirudh and done jointly with Nitish and @yatskar.bsky.social .

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Chaitanya Malaviya @cmalaviya.bsky.social · Jun 6

For instance, miscalibration for vagueness dropped from 51.3% to 28.5% and for jargon from 50.3% to 33.2% after CDA.

Even joint debiasing across multiple biases (length, vagueness, jargon) proved effective with minimal impact on general capabilities.

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Chaitanya Malaviya @cmalaviya.bsky.social · Jun 6

And the results? CDA works!

It significantly reduced average miscalibration (e.g., from 39.4% to 32.5%) and brought model skew much closer to human preferences. All this while maintaining overall performance on RewardBench!

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Chaitanya Malaviya @cmalaviya.bsky.social · Jun 6

So how do we debias models? We propose a simple yet effective post-training method based on counterfactual data augmentation (CDA).

We synthesize contrastive responses that explicitly magnify biases in dispreferred responses, & further finetune reward models on these responses.

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Chaitanya Malaviya @cmalaviya.bsky.social · Jun 6

Indeed, preference models can easily latch on to these subtle data artifacts!

Features that only weakly correlate with human preferences (r_human=−0.12) are strongly predictive for models (r_model=0.36). Points above y=x suggest that models overrely on these spurious cues😮

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Chaitanya Malaviya @cmalaviya.bsky.social · Jun 6

Where do these biases come from?🤔Our analysis suggests they originate from training data artifacts.

For eg, humans preferred structured responses >65% of the time when the alternative wasn't structured. This gives an opportunity for models to learn these patterns as heuristics!

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Chaitanya Malaviya @cmalaviya.bsky.social · Jun 6

How severe is the problem? Using controlled counterfactual pairs, we found that preference models (incl. LLM evaluators) prefer biased responses in >60% of cases (defined as skew) and show high miscalibration (~40%) wrt humans.

Vagueness & sycophancy are especially problematic!

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Chaitanya Malaviya @cmalaviya.bsky.social · Jun 6

Preference models act as proxies for human judgements in alignment (as reward models) & evaluation, but they can be miscalibrated.

We found that they overrely on many idiosyncratic features of AI-generated text, which can lead to reward hacking & unreliable evals. Features like:

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Chaitanya Malaviya @cmalaviya.bsky.social · Jun 6

Ever wondered what makes language models generate overly verbose, vague, or sycophantic responses?

Our new paper investigates these and other idiosyncratic biases in preference models, and presents a simple post-training recipe to mitigate them! Thread below 🧵↓

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Reposted by Chaitanya Malaviya

Manya Wadhwa @manyawadhwa.bsky.social · Apr 22

Evaluating language model responses on open-ended tasks is hard! 🤔

We introduce EvalAgent, a framework that identifies nuanced and diverse criteria 📋✍️.

EvalAgent identifies 👩‍🏫🎓 expert advice on the web that implicitly address the user’s prompt 🧵👇

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Chaitanya Malaviya @cmalaviya.bsky.social · Nov 13

Joint work done @ai2.bsky.social with Joseph Chee Chang, Dan Roth, Mohit Iyyer, Mark Yatskar, @kylelo.bsky.social .

Find these & many more results in our paper: arxiv.org/abs/2411.07237
Use our code: github.com/allenai/Cont...
Explore our data: huggingface.co/datasets/all...

Contextualized Evaluations: Taking the Guesswork Out of Language Model Evaluations

Language model users often issue queries that lack specification, where the context under which a query was issued -- such as the user's identity, the query's intent, and the criteria for a response t...

arxiv.org

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Chaitanya Malaviya @cmalaviya.bsky.social · Nov 13

🤔 How can we use context to learn more about model behavior?

We can study "default" responses from models. Under what type of context does their response get highest score?

We uncover a bias towards WEIRD contexts (Western, Educated, Industrialized, Rich & Democratic)!

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Chaitanya Malaviya @cmalaviya.bsky.social · Nov 13

🤔 Does providing context to evaluators have a substantial effect on evaluation conclusions?

We find that (1) presence of context can improve agreement between evaluators and (2) even change model rankings! 🤯

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Chaitanya Malaviya @cmalaviya.bsky.social · Nov 13

...we then conduct experiments providing context (1) during response generation, (2) during evaluation or (3) both.

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Chaitanya Malaviya @cmalaviya.bsky.social · Nov 13

With ✨Contextualized Evaluations✨, we synthetically generate context as clarifying, follow-up questions to an underspecified query...

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Chaitanya Malaviya @cmalaviya.bsky.social · Nov 13

Underspecified queries can lead to arbitrary evaluation judgments of response quality!

e.g., Given a query “Is coffee good for you?”, how can evaluators accurately judge model responses when they aren't informed about the user’s preferences, background or important criteria?

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Chaitanya Malaviya @cmalaviya.bsky.social · Nov 13

Underspecified queries are prevalent in many datasets used to benchmark language models (e.g., Chatbot Arena, AlpacaEval).

These can be ambiguous (e.g., what is a transformer? ... 🤔 for NLP or EE?), subjective (e.g., who is the best? ... 🤔 what criteria?), and more!

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Chaitanya Malaviya @cmalaviya.bsky.social · Nov 13

Excited to share ✨ Contextualized Evaluations ✨!

Benchmarks like Chatbot Arena contain underspecified queries, which can lead to arbitrary eval judgments. What happens if we provide evaluators with context (e.g who's the user, what's their intent) when judging LM outputs? 🧵↓

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