step,rule,n_before,n_after,n_removed,rationale
1,keep GDPC1 quarters that have a complete (3-month) UNRATE quarterly average,319,314,5,UNRATE starts 1948Q1 (GDPC1 starts 1947Q1); 2025Q4 lacks October 2025 UNRATE
2,drop quarters whose previous calendar quarter is unavailable (first differences undefined),314,312,2,first available quarter and quarters following a dropped quarter
3,restrict to regression window 1960Q1-2019Q4,312,240,72,task-defined sample; no extension of window