Eval researcher: randomize everything for decider models, exploit signals don't hold in real traffic

antoine_chaffin · x · 2026-10-31

Antoine Chaffin argues that decider model evaluations must randomize everything: evals contain many exploitable signals that don't hold on real traffic.

He shares a concrete bias: with long choice lists, models systematically favor the first option, since training data mostly contains tasks with few choices. He tried offsetting letters during training, but that hurt performance on small-choice tasks.

Related event: Mistral researcher: fully randomize everything when evaluating decider models(5 posts)→

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