# Introduction to Machine Learning Week 10 Answers

Q1. The pairwise distance between 6 points is given below. Which of the option shows the hierarchy of clusters created

(a)
(b)
(c)
(d)

Q2. For the pairwise distance matrix given in the previous question, which of the following shows the hierarchy of clusters created
by the complete link clustering algorithm.

• (a)
• (b)
• (c)
• (d)

Q3. In BIRCH, using number of points N, sum of points SUM and sum of squared points SS, we can determine the centroid
and radius of the combination of any two clusters A and B. How do you determine the radius of the combined cluster?
(In terms of N,SUM and SS of both two clusters A and B)

Q4. Statement 1: CURE is robust to outliers.

Statement 2: Because of multiplicative shrinkage, the effect of outliers is dampened.

Q5. Run K-means on the input features of the iris dataset using the following initialization:

Q6. For the same clusters obtained in the previous question, calculate the rand-index. Formula for rand-index:

Q7. a in rand-index can be viewed as true positives(pair of points belonging to the same cluster) and b as true negatives(pair of points
belonging to different clusters). How then, are rand-index and accuracy from the previous two questions related?

Q8. Run BIRCH on the input features of iris dataset using Birch(n clusters=3, threshold=1). What is the rand-index obtained?