MS-DS Master of Data science FREE MS-DS Master of Data science Unsupervised Machine Learning Models Questions and Answers 3

Question 1

What problem does the elbow method help solve when using K-Means clustering?

Accepted Answer

Selecting the optimal number of clusters

Answer

The elbow method plots within-cluster sum of squares against different values of K, and the optimal K is identified at the point where adding more clusters yields diminishing returns.

Question 2

In spectral clustering, what is the primary role of the graph Laplacian matrix?

Accepted Answer

It captures the connectivity structure of the data for eigen-decomposition

Answer

The graph Laplacian encodes the similarity structure of the data as a graph, and its eigenvectors reveal the cluster structure used for partitioning.

Question 3

Which unsupervised method is specifically designed to identify data points that do not conform to expected patterns?

Accepted Answer

Isolation Forest

Answer

Isolation Forest detects anomalies by randomly partitioning data and measuring how few splits are needed to isolate each point, with anomalies requiring fewer splits.

Question 4

What does the Bayesian Information Criterion (BIC) balance when selecting the number of components in a Gaussian Mixture Model?

Accepted Answer

Model likelihood and model complexity

Answer

BIC penalizes the log-likelihood by a term proportional to the number of parameters and log of sample size, preventing overfitting by discouraging overly complex models.

Question 5

In the context of association rule mining, what does the 'lift' metric indicate?

Accepted Answer

The ratio of observed support to expected support if items were independent

Answer

Lift measures how much more often items appear together than expected if they were statistically independent, with values greater than 1 indicating a positive association.

MS-DS Master of Data science Practice Test

MS-DS Master of Data science Practice Test

MS-DS Master of Data science FREE MS-DS Master of Data science Unsupervised Machine Learning Models Questions and Answers 3