what is the usage of parameter “confidence” in operator “Decision Tree”？

Hi @lg21c,

Not sure about the definition of f and q in your probability function. But you can refer to the source code of decision tree and pessimisticpruner.java scripts here
https://github.com/rapidminer/rapidminer-studio-modular/blob/master/rapidminer-studio-core/src/main/java/com/rapidminer/operator/learner/tree/DecisionTreeLearner.java

https://github.com/rapidminer/rapidminer-studio-modular/blob/master/rapidminer-studio-core/src/main/java/com/rapidminer/operator/learner/tree/PessimisticPruner.java

If the tree grows too big, the model is easily overfitting. The confidence level is used to determine whether or not prune the branches based on pessimistic errors.



HTH!

YY