| Method | Training Style | Error Focus | Variance | Bias | Typical Use Case |
|---|---|---|---|---|---|
| Bagging | Parallel (independent) | Reduces variance | ↓↓ | ↔ | High-variance models (e.g., deep trees) |
| Boosting | Sequential | Reduces bias | ↓ | ↓↓ | Weak learners; structured/tabular data |
| Stacking | Hybrid | Leverages diversity | ↓ | ↓ | When you have diverse strong models |
↓ = reduction, ↔ = little change