Under clinical class imbalance, standard uncertainty scores measured dataset sparsity rather than clinical ambiguity, and minority patients paid for it
AspireAI community · arXiv
Selective prediction promises safety by deferring ambiguous cases to human experts, but that only holds if uncertainty scores track clinical ambiguity - and under severe class imbalance they stop doing so. The authors show that standard uncertainty measures become a proxy for class membership instead, systematically penalising minority patients regardless of how individually clear their own case is. Across 56 synthetic conditions and three neurodegenerative cohorts spanning multiple sclerosis, Parkinson's disease and Alzheimer's disease, global metrics either collapsed minority sensitivity or protected the minority at the expense of majority patients, while their correction kept risk bounded and balanced across trajectories. The fix is partly methodological: their corrected rule breaks within-class monotonicity at a threshold of 0.5 and only restores strict monotonicity when combined with threshold-aware metrics, so the conclusion is narrower than 'uncertainty is broken' but more actionable.
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