step,rule,n_before,n_after,n_removed,rationale
1,"keep one row per (iso3, year)",439,416,23,"Exact-duplicate country-years from merging two extractions (same values, different name label)."
2,drop rows with empty life_expectancy,416,415,1,No recorded value; imputation/interpolation is prohibited.
3,keep years 2000-2022,415,415,0,Study window.
4,keep countries with a recorded value in every year 2000-2022,415,345,70,"Excluded incomplete countries: BGD, CHE, ETH, IND, NGA."