Comment by mppm

Cheating and overfitting, as discussed in the article, are the most obvious problems with benchmarking LLMs. But there is also the aspect that, at least for closed models, the tokens still have to be sent to the provider's servers for inference. This makes the holdout set not as held out as it may appear. OpenAI and Antropic probably don't care about your private set of regex benchmarks, but for the headline "closed" benchmarks, I'd be surprised if they haven't collected a nice representative set of "holdout" problems to be examined at leisure.