Dev.to
7/21/2026

Distinguishing wrong from absent
Short summary
The model-drift eval board uses an exact-match grader on a frozen test suite, but this design conflates absent answers (rate limits, refusals, truncations) with wrong ones. A model appeared to drop from 69% to 3% overnight due to 429 rate-limit errors scored as regressions. The board mitigates this by excluding accuracy points only when a run's reliability falls below 50%, avoiding inflated scores on hard prompts that correlate with failures.
- •Exact-match grading conflates absent answers (rate limits, refusals, truncations) with wrong ones
- •A 69% to 3% overnight drop was caused by 429 rate limits, not a real regression
- •Board excludes accuracy points only when run reliability drops below 50%, preventing difficulty-correlated bias
Generated with AI, which can make mistakes.
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