# Data audit
All SHA-256 recomputed with `shasum -a 256`; all match data/README.md.

| file | data rows | cols | first | last | last value | NaN | dup dates | quarter spacing (days) |
|---|---|---|---|---|---|---|---|---|
| vintages/..._2024-01-31.csv | 307 | 2 | 1947-04-01 | 2023-10-01 | 3.3 | 0 | 0 | 90–92 |
| vintages/..._2024-04-30.csv | 308 | 2 | 1947-04-01 | 2024-01-01 | 1.6 | 0 | 0 | 90–92 |
| vintages/..._2024-07-31.csv | 309 | 2 | 1947-04-01 | 2024-04-01 | 2.8 | 0 | 0 | 90–92 |
| vintages/..._2024-10-31.csv | 310 | 2 | 1947-04-01 | 2024-07-01 | 2.8 | 0 | 0 | 90–92 |
| vintages/..._2025-01-31.csv | 311 | 2 | 1947-04-01 | 2024-10-01 | 2.3 | 0 | 0 | 90–92 |
| vintages/..._2025-04-30.csv | 312 | 2 | 1947-04-01 | 2025-01-01 | -0.3 | 0 | 0 | 90–92 |
| vintages/..._2025-07-31.csv | 313 | 2 | 1947-04-01 | 2025-04-01 | 3.0 | 0 | 0 | 90–92 |
| vintages/..._2025-12-31.csv | 314 | 2 | 1947-04-01 | 2025-07-01 | 4.3 | 0 | 0 | 90–92 |
| current_vintage.csv | 318 | 2 | 1947-04-01 | 2026-07-01 | 3.4 | 0 | 0 | 90–92 |
| first_release.csv | 13 | 3 | 2023-07-01 | 2026-07-01 | 3.4 | 0 | 0 | — |

Units: percent change from preceding quarter, SAAR (percentage points of annualised growth).

Anomalies / notes:
- COVID quarters 2020Q2 (≈ -28) and 2020Q3 (≈ +35) are extreme outliers in every vintage (genuine data, not errors). Handled in the model by dropping regression observations with dependent quarter in 2020Q2–2020Q4.
- The 8th origin is 2025-12-31 (not 2025-10-31) because the 2025Q3 advance estimate was delayed by the shutdown; spacing between origins 7 and 8 is 5 months. The h=1 target of origin 8 (2025Q4) was first released in the 2026-02-28 vintage (also delayed).
- Last value of each vintage equals the first release of that quarter (checked in analysis.py).
- Revisions within vintages are visible (e.g. 2025Q1: -0.3 → -0.5 → -0.6 → current 0.1).
- Availability: current_vintage.csv contains post-origin information; it is used only for the revision statistic. first_release.csv is used only as actuals. No input is used in violation of the rules.