1step,rule,n_before,n_after,n_removed,rationale21,Drop 2016-07-15-vintage rows for months covered by the 2026-10-28 vintage,987,957,30,Information rule: use the most recent vintage covering the month32,Keep months in window 2001-01..2026-09,957,309,648,Earlier months only serve as 12-month lags43,Drop window months without a computable g_t (P_t or P_t-12 missing),309,308,1,No interpolation/imputation allowed; missing: 2025-105