Impurity | Task | Formula | Description |
Gini impurity | Classification |
| fi is the frequency of label i at node and C is the number of unique labels |
Entropy | Classification |
| fi is the frequency of label i at node and C is the number of unique labels |
Variance/Mean Square Error(MSE) | Regression |
| yi is the label for an instance, N is the number of instance and μ is the mean given by |
Variance/Mean Absoluter Error (MAE) (Scikit-learn only) | Regression |
| yi is the label for an instance, N is the number of instance and μ is the mean given by |