WCB (SecureBio)
Science
SecureBio's World-Class Biology benchmark, 96 text-only open-ended questions graded against an expert rubric by a model grader. Evaluated in Inspect with zero-shot prompting, usually over 10 runs. SecureBio doesn't state how refusals enter accuracy. Claude Opus 5.5 prints 54.5% with 74.4% refused, more than it could score if refusals counted as wrong, so accuracy appears to cover answered questions only and each model's denominator differs. These scores aren't comparable with other runs of the test, which is why this is a diagnostic.
Benchmark source: Securebio