1# Data audit (P1)2| file | SHA-256 | rows | cols |3|---|---|---|---|4| data/design.csv | b1a17a529973e7994bbedad5ec1bc73fe968c777301ca8745657ea300e3c74f0 (matches bundle.json) | 30 | 3 |56Schema: i (int64, 1..30, unique, sequential), x (float64, dimensionless, range -1.3942..1.9919, mean 0.2823, sd 0.8212), sigma (float64, dimensionless, range 0.6034..1.7903, all > 0).7No dates (synthetic fixed design). Missing values: 0. Duplicate rows: 0.8Anomalies: none. Note: sigma increases with |x - c| (roughly quadratic in x; largest at extreme x), i.e. heteroskedasticity is concentrated at high-leverage points — the setting where conventional SEs understate variability.9Availability: the file is the only permitted input; no violation. No exclusions applied.10