MS-DS Master of Data science Unsupervised Machine Learning Models 2

Question 1

Which linkage criterion in hierarchical clustering tends to produce compact, spherical clusters?

Accepted Answer

Ward's linkage

Answer

Ward's linkage minimizes the total within-cluster variance at each merge step, producing compact and spherical clusters.

Question 2

In DBSCAN, a point is classified as a 'border point' when it:

Accepted Answer

Has fewer than MinPts neighbors within epsilon but is reachable from a core point

Answer

A border point has fewer than MinPts neighbors within epsilon but falls within the epsilon-neighborhood of a core point.

Question 3

What does the reconstruction error in an autoencoder measure?

Accepted Answer

The difference between input and decoder output

Answer

Reconstruction error measures how well the decoder can reproduce the original input from the compressed latent representation.

Question 4

Which of the following best describes the 'manifold hypothesis' as it relates to dimensionality reduction?

Accepted Answer

High-dimensional data lies on or near a lower-dimensional manifold embedded in the high-dimensional space

Answer

The manifold hypothesis states that real-world high-dimensional data concentrates near a lower-dimensional curved surface (manifold).

Question 5

In topic modeling with Latent Dirichlet Allocation (LDA), what does the Dirichlet prior control?

Accepted Answer

The sparsity of topic-document and word-topic distributions

Answer

The Dirichlet hyperparameters alpha and beta control the sparsity of per-document topic distributions and per-topic word distributions respectively.

MS-DS Master of Data science Practice Test