Format Sensitivity Index: How Simple Prompt Changes Can Flip LLM Leaderboards

It is a metric that quantifies the variance in an LLM's accuracy when using different prompt wrappers, revealing the model's sensitivity to formatting changes.

They imply that organizations in the region should not rely on a single benchmark; models should be tested across multiple wrappers to ensure accurate results.

Yes, the study shows that wrapper choice can change model scores enough to reverse leaderboard conclusions.

Report wrapper variance and compliance metrics like FSI and PSI, and use standardized protocols to improve evaluation reliability.