1step,rule,n_before,n_after,n_removed,rationale20_read,rows read from firm_panel.csv,2140,2140,0,all data rows (excluding header)31_drop_rating_2025,drop column rating_2025 (known 2025 > end of year t),2140,2140,0,final-vintage field built from realised default history through 2022 and sample-average leverage; look-ahead / outcome leakage; column removal only42_drop_exact_duplicates,remove exact duplicate rows (keep first),2140,2100,40,assembly error: identical firm-year rows repeated53_drop_missing_outcome,drop firm-years with default_next not observed,2100,1800,300,outcome year t+1 not observed at data cut (end 2022); missing years: [2022]; not imputed64_drop_missing_predictors,drop rows with missing leverage/cash_ratio/log_sales,1800,1800,0,complete-case on predictors7