A driftless-random-walk closed form was tried first and backtested wrong
against 3 years of real exchange history (overstated touch probability
2-4x, confounded by discrete daily-VWAP sampling and real mean-reversion).
Replaced with puga.history.empirical_touch(): a non-parametric estimator
measuring first-passage directly from a ticker's own history, conditioned
on current state (trailing-60d z-score) since mean reversion's effect
depends on where price is now, not just move size. Queue-depth (existing
resting quantity) folds in as a deterministic shift of the hitting time,
not a max, ranking by the resulting hit_factor rather than a point
estimate of median days (which created a false cliff at the 50%-touched
threshold). Optional fixed-horizon right-censoring avoids recency bias
in "never reached" samples.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
dodoxandClaude Sonnet 5
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