Ensemble Stacking & Blending are meta-learning frameworks combining heterogeneous base models (LightGBM, XGBoost, CatBoost, Deep MLPs, Logistic Regression) with orthogonal inductive biases to minimize variance and push performance boundaries; 1) Stacking enforces strict K-Fold Cross-Validation: base models trained on
K−1 folds generate out-of-fold (OOF) prediction logits on the holdout fold; these concatenated leak-free OOF predictions form the meta-feature dataset training a Level-2 Meta-Learner (typically Logistic Regression or shallow Ridge); 2) Blending splits data into train and holdout sets, training base models on train and meta-learners on holdout predictions (simpler but discards data efficiency).