1step,rule,n_before,n_after,n_removed,rationale21,Months 2001-01..2026-09 of the spliced series,309,309,0,Analysis window defined in TASK.md (one row per calendar month).32,Drop months whose index level P_t is missing in all vintages,309,308,1,No interpolation/imputation allowed; 2025-10 has no value in the 2026-10-28 vintage.43,Drop months whose lagged level P_{t-12} is missing,308,308,0,g_t requires both levels; lag of 2026-10 would be 2025-10 but 2026-10 is outside the window.5