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Practical Predictive Analytics by Ralph Winters

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Growing the tree

Our original node always starts at the root of the tree. In the preceding diagram, the first node merely starts with a description of how the population breaks down by gender. In this case, females make up the majority class at 58% of the population. The goal in decision of tree algorithms is to always grow a tree and improve predictions. So, at this point, we want to do better than 58% prediction for gender.

As we grow the tree, two questions will always need to be taken into consideration:

  • Which variable will best improve the prediction for each of the classes of the target variable at that point?
  • For that variable, what is the best split point that will segment a categorical variable into two parts, or divide a continuous ...

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