step,rule,n_before,n_after,n_removed,rationale
1,drop entities with region == 'Aggregates',2349,1953,396,analysis population is countries/economies only (TASK rule)
2,keep analysis year 2023 (most recent year with >=150 complete countries),1953,217,1736,estimand is a single cross-section in the analysis year
3,drop countries with missing gdp_pc_ppp or life_expectancy,217,197,20,no imputation (TASK rule)