# Data audit

• Schema: date (str YYYY-MM-DD), yield_5y (float, percent), post_cut (int).
• Date range 2010-01-04 → 2019-12-31, strictly increasing, 0 duplicate dates, 0 missing values in any column.
• yield_5y: min 0.48, max 3.20, mean 1.574 %, plausible.
• Calendar gaps between rows: 1d ×1962, 2d ×10, 3d ×440 (weekends), 4d ×79, 5d ×6 (holiday stretches) — consistent with business-daily data; no long outages.
• Rows per year: 249–250 for each of 2010–2019.
• post_cut: 2498 zeros, 0 ones. The README states the retrieval was end_date=2019-12-31, so the file contains no dates on or after 2020-03-04. The treated window is empty and the 120-day pre window (defined relative to the first flagged day) is undefined.
• Availability rules: no violation in the inputs (no future information); the problem is missing coverage, not leakage.
• Decision: estimand not computable → premise_invalid, feasibility infeasible; effect, CI, model RMSE and n_analysed set to null. Do NOT substitute e.g. the last 120 days of 2019 or a different event date (that would be a proxy/redefinition of post_cut). The whole-file baseline mean change is still reported as required.