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Machine Learning Techniques · Quiz 2 · 3 Aug 2025 · May 2025 term

Question 15: Suppose you want to build a decision tree to help diagno…

Question 15

+4 marksNumerical answer

Suppose you want to build a decision tree to help diagnose a certain disease based on patient data. You have a dataset of 1000 patients labeled as either “positive” or “negative”. Here, positive represents patients with the disease and negative represents no disease. One of the feature used to diagnose is headache.
Below is the breakdown of the patients reporting headache:
Headache present: 300 positive, 50 negative
Headache not present: 100 positive, 550 negative

Use the following values if required:

  • log⁡2(0.4)=−1.32\log_2(0.4) = -1.32
  • log⁡2(0.6)=−0.74\log_2(0.6) = -0.74
  • log⁡2(0.86)=−0.22\log_2(0.86) = -0.22
  • log⁡2(0.14)=−2.84\log_2(0.14) = -2.84
  • log⁡2(0.15)=−2.74\log_2(0.15) = -2.74
  • log⁡2(0.85)=−0.23\log_2(0.85) = -0.23

Note: Use log⁡2\log_2 for the entropy calculations.

Based on the above data, answer the given subquestions.

What is the information gain for choosing the feature “headache” for splitting at the root node? Enter the answer correct to two decimal places.

Show answer

Correct answer: 0.36 (accepted within ±0.02)

See the whole paperTake it as a mock test

Question 15 of 15 in the IIT Madras BS Machine Learning Techniques (MLT) Quiz 2 paper sat on 3 Aug 2025, in the May 2025 term (IIT M DEGREE AN EXAM QDB2 03 Aug 2025). It carries 4 marks.

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