# Benchmark redundancy

Pruning a benchmark because it correlates with another may discard exactly the signal that separates frontier models. Across 4,497 models on Open LLM Leaderboard v2, BBH and GPQA correlate at 0.861 overall, yet conditional Spearman falls to 0.434 among the top 20% and to -0.278 among the top 5%; 7 of 15 pairs are best fit by zero-tail-dependence Frank copulas, so high bulk correlation does not imply agreement at the frontier.

Pruning a benchmark because it correlates with another may discard exactly the signal that separates frontier models. Across 4,497 models on Open LLM Leaderboard v2, BBH and GPQA correlate at 0.861 overall, yet conditional Spearman falls to 0.434 among the top 20% and to -0.278 among the top 5%; 7 of 15 pairs are best fit by zero-tail-dependence Frank copulas, so high bulk correlation does not imply agreement at the frontier.