how to calculate accuracy from decision trees?

decision-tree
Chao Li picture Chao Li · Jan 24, 2018 · Viewed 21.3k times · Source

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Hi, I am taking a course on Coursera and came into this question. My answer is 1-(4048+3456)/8124=0.076. However, the answer is 0.067. Anybody can help me to solve this? Thank you!!

Answer

patricio picture patricio · Feb 5, 2018

Accuracy: The number of correct predictions made divided by the total number of predictions made.

We're going to predict the majority class associated with a particular node as True. i.e. use the larger value attribute from each node.

So the accuracy for:

  • Depth 1: (3796 + 3408) / 8124
  • Depth 2: (3760 + 512 + 3408 + 72) / 8124

Depth_2 - Depth_1 = 0.06745

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