Machine Learning Clustering 4

Question 1

In a Gaussian Mixture Model, what does each component's covariance matrix control?

Accepted Answer

The shape and orientation of the cluster

Answer

The covariance matrix determines whether a Gaussian component is spherical, elongated, or rotated in any direction.

Question 2

Which cluster validity index penalizes clusters that are far from each other and rewards clusters with low intra-cluster scatter?

Accepted Answer

Calinski-Harabasz Index

Answer

The Calinski-Harabasz Index is the ratio of between-cluster dispersion to within-cluster dispersion; higher values indicate better-defined clusters.

Question 3

What does the 'elbow method' help determine in K-Means clustering?

Accepted Answer

The appropriate number of clusters K

Answer

The elbow method plots inertia vs. K and looks for the point where adding more clusters yields diminishing returns.

Question 4

Which type of hierarchical clustering starts with all points in one cluster and recursively splits them?

Accepted Answer

Divisive clustering

Answer

Divisive hierarchical clustering uses a top-down approach, splitting the single large cluster into smaller ones at each step.

Question 5

What is the role of the minPts parameter in DBSCAN?

Accepted Answer

It defines the minimum number of points required to form a dense region

Answer

A point is a core point in DBSCAN if at least minPts points (including itself) fall within its epsilon-radius neighborhood.

Machine Learning Practice Test