1step,rule,n_before,n_after,n_removed,rationale21_drop_column_rating_2025,drop column rating_2025 (known only in 2025),2140,2140,0,Final-vintage field assigned in 2025 using realised default history through 2022 and sample-average leverage; not known at end of year t (look-ahead leakage).32_drop_exact_duplicates,drop rows identical to an earlier row on all 7 columns,2140,2100,40,Assembly error: firm-year rows repeated verbatim; keeping them would double-count observations.43_drop_missing_outcome,drop firm-years with default_next empty,2100,1800,300,Outcome year t+1 not observed by the data cut (end 2022); occurs in years [2022]. Outcomes not imputed.54_drop_missing_predictors,drop rows with missing leverage/cash_ratio/log_sales,1800,1800,0,Complete-case requirement for OLS (no rows affected if 0 removed).6