1step,rule,n_before,n_after,n_removed,rationale21,year_window: keep rows with year in 2000-2022,439,439,0,Study period.32,"dedupe: one row per (iso3, year)",439,416,23,Each country counted once per year; duplicates were identical.43,drop_missing: drop country-years with empty life_expectancy,416,415,1,No imputation allowed.54,balanced_panel: keep countries with a recorded value in every year 2000-2022,415,345,70,"Balanced panel; removed countries: BGD, CHE, ETH, IND, NGA."6