Improvement in reasoning performance of LLMs over time

If you tried using ChatGPT when it first came out and concluded that it wasn't much use for a scientific reasoning task, it might be time to try it again. For the task I semi-described in the previous post, it worked exceptionally well. Here I've tried to gather some information on what's changed between the original release and today, and how you can keep track of improvements in performance.

Background

The LLM developed by OpenAI is called GPT ("Generative Pre-trained Transformer"). It was released as a chatbot publicly in Nov 2022 and it changed the world (for better or worse). This release was already version 3.5. Since then, LLMs have been developed by several companies/groups, often with new versions multiple times a year.

For scientific problems, a particular landmark was the development of LLMs with 'reasoning' capability; the ability to perform multi-step logical problem-solving. OpenAI's o1 model (Sept 2024) was the poster child for this. Currently OpenAI's GPT-5.2 represents the state-of-the-art, though the upcoming Gemini 3 Pro (currently in preview) may have the edge on it. But how do we know this?

The benchmark

LLM benchmarks exist for coding tasks, solving maths problems, medical exams and so forth, but for reasoning, a single benchmark - the GPQA benchmark - has established itself as the gold standard, in particular the "Diamond" subset thereof. GPQA stands for "Google-Proof Q&A". In Nov 2023, Rein et al (New York Uni) published a preprint describing how they employed incentivised PhD-level contractors to put together a set of scientific multiple-choice questions (4 choices) covering biology, chemistry and physics that could not be answered by Google searches and required domain knowledge. Random answering scores 25%; PhD-level non-scientists (note: my interpretation) with access to the internet scored 34%; PhD-level scientists scored 69.7% (note: I don't see this figure in the preprint, but it is widely quoted).

Just a note about the 69.7%. The exact figure doesn't matter, but there's some idea that beating this figure means superhuman results. Um, no. An expert in biology is not expected to answer the physics questions very well. Are coding LLMs superhuman if they are better than a Python expert at answering Java questions? If they beat an expert at their own area of expertise, now that would be impressive. Given that it is expected that three experts sitting together would get 100%, it follows that the benchmark is not capable of measuring superhuman performance (this is actually mentioned at the end of the preprint). A more interesting number perhaps is 55% which roughly gives a measure of how well a scientist does when answering questions outside of their domain (I estimated this value by subtracting the 33.3% of correct answers inside the expert's domain from 69.7% and scaling it up, i.e. (69.7 - 100/3) / 2 * 3).

The results

The key point is that this is a set of difficult scientific questions that require reasoning, and that we can track the performance of LLMs over time against this benchmark. Here are the results for OpenAI models taken from an analysis by Epoch AI. Each individual model was tested 16 times, with the typical stderr around 2%:

• GPT-3.5 (Nov 2022): 28% (taken from here) 
• GPT-4 (Mar 2023): 36%
• GPT-4 Turbo (Nov 2023): 42%
• GPT-4o (Aug 2024): 49%
• o1-mini (Sep 2024): 62% (at "high" reasoning setting)
• o1 (Dec 2024): 76% (medium)
• o3-mini (Jan 2025): 77% (high)
• GPT-4.1 (Apr 2025): 67% (note: the 4.1s are a non-reasoning model)
• GPT-4.1 mini: 66% (this is a smaller/faster/cheaper version of GPT-4.1)
• GPT-4.1 nano: 49%
• GPT-5 (Aug 2025): 85% (medium)
• GPT-5-mini: 72%
• GPT-5-nano: 67%
• GPT-5.1 (Nov 2025): 85% (medium) 88% (high)
• GPT-5.2 (Dec 2025): 88% (medium) 88% (high) 91% (xhigh)

Conclusion

In summary, there have been major improvements over the last three years in terms of reasoning. Nor has it reached a peak. Gemini 3 Pro Preview (Nov 2025) is reported as 93%. In August, a new kid on the block, Autopoiesis, reported 92.4% for their Aristotle X1 Verify model (but this is not publicly available nor independently verified). It feels like we will soon get to the point where the field will need a more difficult benchmark.

Finally, it should be noted that pure performance is not the only relevant criteria. Price, energy usage, and ability to run locally will also be important considerations. Let's see what 2026 brings.

Image credit: Epoch AI, CC BY, https://epoch.ai/benchmarks/gpqa-diamond.

Classifying PubMed Abstracts with LLMs

I've just spent the Christmas playing with the OpenAI API, and I am impressed at what is now possible. There are 38M PubMed Abstracts (*); through judicious use of keyword filters (bringing it down to 250K) followed by a pass through a cheap model (bringing it down to 3.5K), I have essentially categorised all of the abstracts of interest with GPT-5.2 for less than $20 (**). Even leaving out the cheaper model and going directly to GPT-5.2 would still only be less than $200.

(If you read this before Jan 11 2026, and think that this topic sounds interesting, I encourage you to apply for openings in my group !)

This is what's known as a reasoning task. Here is the general prompt that I used, except that I have hidden some of the details (the definition section was suggested by ChatGPT as an improvement but I don't know that it helped).

Based on this article title and abstract, does the associated paper describe X?

Definitions:
- Y
- Z

Instructions:
- Reply with exactly one of: Yes, No, or Maybe.
- If the answer is No, reply with only: No
- If the answer is Yes or Maybe, briefly justify your answer by quoting specific words or phrases from the title or abstract as evidence.
- Do not infer beyond what is explicitly stated in the text.

When running it through GPT-5.2, I used slightly more complicated instructions in order to identify primary research data::

Instructions:
- Reply with exactly one of: Yes (primary), Yes (secondary), No, or Maybe.
  - Yes (primary) indicates that the paper is a primary reference for X, rather than being a review article or mentioning it as background
- If the answer is No, reply with only: No
- Otherwise, briefly justify your answer by quoting specific words or phrases from the title or abstract as evidence.
- Do not infer beyond what is explicitly stated in the text.

The cheaper/faster/less accurate model I used was GPT5-Nano. As a validation, I put all of the 2023 and 2024 abstracts through GPT-5.2 and only found a single additional "Yes" (on top of the 53 found by GPT5-Nano), and I'm not convinced about that particular case. GPT-5.2 was definitely required though as a final pass to reduce false positives; I passed all of the Yeses and Maybes from the Nano through to GPT-5.2 and it mostly trimmed down the Yeses and didn't promote the Maybes.

Run-time is somewhat dependant on how many batches you need to use as there is an overhead associated with each batch. When you sign up for API access, you start on Tier 1 and need to use lots of batches which must be run serially to avoid queue limits. In one case, I ran 75 batches of 3000 with GPT5-Nano; each one took 20 mins on average which was fine, but the API SLA only guarantees an answer within 24h would would be bit of a problem. After 7 days, I was bumped up to Tier 3 and it's possible that I could do the same thing in a single batch now. For example, on Tier 3, I ran 4 batches of 10000 with GPT5.2, each one taking 1h.

Given that the prompt above lends itself to many questions, you can use the details I've provided to get an idea of what might be possible for your questions of interest and for what budget. The trickiest part right now is dealing with the batch API, queue limits, and JSON, which can all be a bit tedious until you have something in place. Indeed, it feels like the sort of thing where there's a business opportunity to provide a biologist-friendly interface to abstract (***) this away. In any case, it's easy to predict that in 2026 we will be seeing less of BioBERT and similar models, and more adoption of LLMs.

Footnotes:

* in the 2025 baseline file - soon to be updated.

** $17.07 for GPT5-Nano over 250K abstracts and $1.82 for GPT-5.2 over 3.5K abstracts.

*** for once no pun intended!