1step,rule,n_before,n_after,n_removed,rationale21_dedup_iso3_year,"keep one row per (iso3, year)",439,416,23,same country (iso3) assembled twice under two name spellings with identical values32_drop_countries_missing_rows,"drop countries without a row for every year 2000-2022 (BGD, ETH, IND, NGA)",416,368,48,not observed in every year; balanced-panel estimand requires all 23 years43_drop_countries_with_empty_value,drop countries with an empty life_expectancy cell in some year (CHE),368,345,23,missing value may not be imputed; country not in balanced set5