2.4. Model Evaluation
The model evaluation section consisted of 3 parts, (1) internal validation, (2) external validation with data imputation, and (3) sensitivity analysis. In internal validation, we performed receiver operating characteristics (ROC) analysis and bootstrap-estimated calibration in both training data and validation data. In external validation, we combined the TCGA-LUAD and TCGA-LUSC. The necessary variables in the external cohorts were used and missing values were imputed by heterogeneous incomplete variational auto-encoder (HI-VAE) (