stats Design

Statistics are pure transformations over explicit arrays. Raw event storage is owned by sinks, so filtering cannot rewrite historical observations.

compare_paired currently uses median paired delta and a practical percentage threshold. Its default Interval continues to store delta quartiles for backward-compatible descriptive analysis. compare_paired_with_bootstrap resamples paired deltas with replacement and reports a deterministic percentile interval; callers must provide the seed, resample count, and confidence level.

Invalid bootstrap input is represented by BootstrapError. The implementation is a percentile bootstrap, not bias-corrected accelerated (BCa), studentized, or hierarchical bootstrap. Empty inputs to summarize remain neutral, while empty bootstrap samples are rejected.