# Data audit (P1)
- File: data/design.csv, SHA-256 b1a17a529973e7994bbedad5ec1bc73fe968c777301ca8745657ea300e3c74f0 (matches bundle.json).
- 30 rows x 3 columns: i (int, 1..30 consecutive), x (float, dimensionless, range −1.3942..1.9919, mean 0.2823), sigma (float, dimensionless, range 0.6034..1.7903, all > 0).
- Missing values: 0. Duplicate rows: 0. No dates (fixed design, no time dimension).
- Pattern: sigma is roughly a convex (U-shaped/quadratic-like) function of x, largest at extreme x — the classic case where conventional OLS SE understates Var(b̂) because high-leverage points have high variance.
- No availability-rule violations: the only input is the permitted design file. No exclusions applied.