What is the role of entropy decrease curve in tree growth analysis?

Entropy decrease curve helps analyze how quickly impurity reduces as the tree grows.

As a decision tree grows, each split reduces entropy (or Gini impurity). The entropy decrease curve tracks this reduction across depth levels. Initially, entropy drops rapidly as informative splits are made. Later, the curve flattens, indicating diminishing returns and potential overfitting if growth continues. This curve is useful for deciding pruning thresholds and optimal depth selection.