# Contract — F1-conf-01

Question. 12-month % growth of CPIAUCSL (SA) for each month 2001-01..2026-09 and summaries. Estimands. g_t = 100*(P_t/P_{t-12} - 1), P from the most recent vintage covering the month (2026-10-28 vintage for 2014-01..2026-09, 2016-07-15 vintage otherwise). Summaries: mean over window, means over 2001-01..2013-12 and 2014-01..2026-09, g at 2014-06, 2016-07, 2020-05, 2022-06, 2026-09, max/min and months. Meaningful under the assumption that splicing two vintages is acceptable (both on 1982-84=100 base; for 2014 months the ratio mixes vintages, as prescribed by the rule). Outputs. out/results.json (keys per TASK.md table), out/analytic.csv (date,cpi,cpi_lag12,vintage_used,growth_12m; n_analysed rows), out/exclusions.csv, out/report.md (6 sections), out/analysis.py, out/claims.json. Information rules. Latest-vintage-per-month; no interpolation/imputation; missing g_t reported and counted; only data/ files. Invalidity. Using the hand-assembled file as-is (may contain errors), imputing missing levels, using old-vintage values where the new vintage covers the month.