ensembles-heterogeneous-vlms-answering-multimodal-multiple-choice-questions-entropy-uniformly CLM-0383
mechanismsingle paperReviewed by AI

For ensembles of heterogeneous VLMs answering multimodal multiple-choice questions, the entropy of a uniformly pooled distribution over semantic-equivalence classes of sampled responses ranks wrong answers above right ones better than majority-vote entropy or picking the single lowest-entropy model, and the advantage grows with ensemble size; the same signal measured at the subagent evidence layer of a multi-step multi-agent system only ranks system failures slightly above chance.

Capability: Saying it does not know

Observed on

Training-free, no logits needed; 400 ScienceQA and 200 MMMU-Pro samples; 10 samples per model at temperature 1.0; three-model ensembles drawn from 8 small open, 6 large open, 6 com.

Sources

  • Validated by: AUROC for prediction-error detection and AUARC for abstention against majority voting, naive lowest-entropy selection, and mean single-VLM reference: collective uncertainty 0.764 AUROC / 0.889 AUARC in the small regime (4.7-15.8 points over baselines), 0.906/0.987 large, JSD best in commercial at 0.819/0.910; pooled prediction accuracy up 13.0, 5.6, 8.7 points over the average single VLM; trajectory-level 0.619 AUROC / 0.699 AUARC.. [truncated]
Reviewed by AI (Claude Opus 5)Last checked: 2026-10-17Evidence activity: not checked yet
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Notes

Drafted from the paper by a model and filed unreviewed. Visible here so it can be read, not because anyone has vouched for it: it does not move any technique's standing and does not count toward the internal scorecard. Drafted confidence: medium. Falsifier as drafted: An evaluation where pooled semantic entropy over several VLMs ranks errors no better than majority-vote entropy or the best single model's semantic entropy, or where its AUROC advantage shrinks rather than grows as models are added.