1step,rule,n_before,n_after,n_removed,rationale21,"Drop duplicate (iso3, year) rows (identical values)",439,416,23,Panel assembled from two extractions; some countries appear twice under different names. iso3 identifies the country; one observation per country-year.32,Drop country-years with empty life_expectancy,416,415,1,Empty cell = no recorded value; no imputation allowed.43,Keep only countries with a recorded value in every year 2000-2022,415,345,70,"Balanced-panel estimand; excluded incomplete countries: BGD, CHE, ETH, IND, NGA."5