# 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, sub-period means 2001-01…2013-12 and 2014-01…2026-09, g at 2014-06, 2016-07, 2020-05, 2022-06, 2026-09, max/min and their months. Meaningful as descriptive statistics of the published series; for t in 2014-01…2014-12 the ratio mixes two vintages (P_t from 2026 vintage, P_{t-12} from 2016 vintage) — that is what the rule prescribes; documented. Outputs: out/results.json (task_id, first_growth_month, last_month, n_months_growth, n_months_missing_growth, n_analysed, mean_growth_12m, mean_growth_12m_2001_2013, mean_growth_12m_2014_2026, growth_2014_06, growth_2016_07, growth_2020_05, growth_2022_06, growth_2026_09, max_growth_12m, max_growth_month, min_growth_12m, min_growth_month, feasibility, feasibility_reason, data_issues, n_input_rows, random_seed); out/analytic.csv; out/exclusions.csv; out/report.md; out/analysis.py; out/claims.json. Availability rules: per-month most recent vintage; no interpolation/imputation; missing g_t reported and counted; only data/ files. Invalidity: using the hand-assembled file as source if it has errors; imputing missing months; using old-vintage values where the new vintage covers the month.