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Disagreement among frontier LLMs on real-world fact-checks

lenz.io

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Re: Disagreement among frontier LLMs on real-world fact-checks

#231

Why did they exclude Grok? Given the published philosophical differences in how Grok is trained, it would provide an interesting data point. You can argue all day about those differences, but missing this opportunity to observe them in an objective way is disappointing.

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Re: Disagreement among frontier LLMs on real-world fact-checks

#232
post #48
post #11

Here's the prompt they used: Classify this claim as of : " " Output exactly one label: True, Mostly True, Misleading, or False. No explanations, no qualifiers. The claims look like this: https://lenz.io/research/llm-disagreement/data.csv I put that in Datasette Lite to make it easier to explore. Here's an example of a disagreement: https://lite.datasette.io/?csv=https%3A%2F%2Fstatic.simonwil... The claim was "All alm…

This seems like another case where the models are acting like humans. Assuming they were not allowed to search the web, I wouldn't expect the models to necessarily have detailed information about all of these things directly in their training set. As large as they are, they are only so large, and they only have so much room for "information storage" in them, and there's a lot more things they need to fit into their n…

Can you share what you mean by this?

> when using dedicated AI resources that I'm paying for

Are there API-based search providers that structure their results differently?

Re: Disagreement among frontier LLMs on real-world fact-checks

#233
post #11

Here's the prompt they used: Classify this claim as of : " " Output exactly one label: True, Mostly True, Misleading, or False. No explanations, no qualifiers. The claims look like this: https://lenz.io/research/llm-disagreement/data.csv I put that in Datasette Lite to make it easier to explore. Here's an example of a disagreement: https://lite.datasette.io/?csv=https%3A%2F%2Fstatic.simonwil... The claim was "All alm…

I had a hunch that opus 4.7 hedged more than other models - and it turns out it's true model total_claims hedged_count hedged_pct claude-opus-4-7 1000 451 45.1 sonar-pro 1000 391 39.1 gpt-5.4 1000 277 27.7 gemini-3-retrieval 1000 129 12.9 gemini-3-pro 1000 60 6.0 datasette query here https://lite.datasette.io/?csv=https%3A%2F%2Fstatic.simonwil...

This is in line with my observations and tests as well. Also supported by the distribution of the verdicts across the 4-buckets -- Gemini uses the middle buckets (Mostly True and Misleading) much less often - 6% combined for Gemini w/o search. And Opus uses them the most - 45% combined. Looks like Gemini is calibrated to be confident and Opus to be careful.

Re: Disagreement among frontier LLMs on real-world fact-checks

#234
post #208

Earlier quoted context omitted.

This is a great example of why prompt engineering is still relevant. Without providing definitions and examples and a well defined rubric, you’re going to see different models disagree by a level in either direction. When you get more prescriptive the models tend to agree better. I’ve experimented with AI grading for undergraduate math courses, and see basically the same thing. If you just tell the AI “grade this pro…

That's a valid point. During the preliminary research, we did try also more explicit prompts (with explanation for each of the 4 buckets), as well as a five-bucket rubric (with Abstain option). Will show in a follow-up paper how the concise vs explicit prompt impacts the distribution of the verdicts and the level of disagreement. One issue to note with the longer prompts is that they open to much room for discussion…

The other thing I suspect is that "Just give me True/False" cuts off a large amount of the search space a modern-day LLM uses to help it answer questions (you can see it in reasoning traces but the act of writing the explanation helps guide it toward a better answer and gives it better likelihood it backtracks on a bad decision).

If you let it spew out an explanation along with the answer, I'm curious if the accuracy will improve (I suspect it will).

Re: Disagreement among frontier LLMs on real-world fact-checks

#235
post #11

Here's the prompt they used: Classify this claim as of : " " Output exactly one label: True, Mostly True, Misleading, or False. No explanations, no qualifiers. The claims look like this: https://lenz.io/research/llm-disagreement/data.csv I put that in Datasette Lite to make it easier to explore. Here's an example of a disagreement: https://lite.datasette.io/?csv=https%3A%2F%2Fstatic.simonwil... The claim was "All alm…

An interesting tangent on this is: how many answers to these (or any number of factual questions) do you (as in anyone) actually know. Not believe you know, but actually know.

Knowing something is different to reading about something, or hearing something from someone. And yet this is often confused as knowledge. In this way are we all that different from AI - we have some data and we regurgitate it as knowledge. Bad data, wrong answer. Except humans can also throw in some emotion to really muddle things up. :)

Re: Disagreement among frontier LLMs on real-world fact-checks

#236

Why did they exclude Grok? Given the published philosophical differences in how Grok is trained, it would provide an interesting data point. You can argue all day about those differences, but missing this opportunity to observe them in an objective way is disappointing.

Title says “Frontier” which would exclude Grok. Grok is trained to have a bias, which a lot of people like, but it’s not meant to be accurate.

How do you know it is trained to have a bias? In fact can I ask you to provide a single reproducable answer right now?

Re: Disagreement among frontier LLMs on real-world fact-checks

#238
post #203

I don't get why everyone is hellbent on getting LLMs to perform fact checking. This is not the technology for it. Sure it might sorta kinda work in some circumstances. That doesn't make it a good fit. Think of it like buying a refrigerator for storing clothes.

But people use it for that. So what's your point?

Re: Disagreement among frontier LLMs on real-world fact-checks

#239
post #11

Here's the prompt they used: Classify this claim as of : " " Output exactly one label: True, Mostly True, Misleading, or False. No explanations, no qualifiers. The claims look like this: https://lenz.io/research/llm-disagreement/data.csv I put that in Datasette Lite to make it easier to explore. Here's an example of a disagreement: https://lite.datasette.io/?csv=https%3A%2F%2Fstatic.simonwil... The claim was "All alm…

Another (IMO fatal) error is they don’t attempt to measure within-model variance.

The thing you find when you actually wire up a rigorous eval is that with tool calls like web search you are wide open to infra issues, flakes, and all sorts of non-determinism.

They really should be breaking out the numbers for the 3 without search (kinda meaningless for recent factual claims after knowledge cutoff) vs search agents. Lack of a “I don’t know” option completely invalidates results for the non-search models; they are basically guessing what seems like a probable answer, since they don’t know and aren’t allowed to say that.

I do agree the forced choice and “weak / strong” variants inflate the headline stat. To make that distinction you need a much more rigorous prompt, likely including ICL examples to illustrate what you mean by “mostly” instead of leaving this to the model to define.

Re: Disagreement among frontier LLMs on real-world fact-checks

#240
post #141
post #135

Earlier quoted context omitted.

@john_strinlai @gcr, depends on the application. In many cases an "I don't know" answer is indeed better than a forced answer. But in many production systems, LLMs generate content/response anyway. Although inheriting the messiness of the real-world, the majority of these claims are objective enough to be classifiable by human experts with access to research. Plan to human-label the 1,000 claims and publish a follow-…

If you're going to run this again I also recommend encouraging the model to provide its rationale and then having it return the true/false/misleading/mostly-true/abstain at the end of its response. Models give much better answers when they can "think out loud" before answering, and storing that rationale will make it easier to understand why they picked different answers for ambiguous questions.

Good point. Processing the substance of the answer might be too labor-consuming (1,000 claims x 5 models), but "thinking out loud" might improve the quality of the answers indeed. And we can still force/ask them to respond with a clear verdict at the end of their reasoning, as per the chosen rubric.
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