DMC Data Analysis & Modeling Techniques 2

Question 1

In association rule mining, which measure indicates how much more often items A and B occur together than expected if they were independent?

Accepted Answer

Lift

Answer

Lift = confidence(A→B) / support(B); values above 1 indicate positive association.

Question 2

A model scores 98% training accuracy but 71% on held-out data. What is the most likely issue?

Accepted Answer

Overfitting

Answer

A large gap between training and validation performance is the classic sign of overfitting.

Question 3

Which clustering algorithm can identify arbitrarily shaped clusters and flag noise points without requiring the number of clusters in advance?

Accepted Answer

DBSCAN

Answer

DBSCAN groups density-connected points and labels low-density points as noise.

Question 4

Which impurity measure is used by the CART algorithm for classification splits by default?

Accepted Answer

Gini index

Answer

CART uses the Gini index for classification trees and variance reduction for regression trees.

Question 5

What is the main purpose of principal component analysis (PCA)?

Accepted Answer

Reduce dimensionality while retaining maximal variance

Answer

PCA projects data onto orthogonal components that capture the greatest variance.

DMC - Data Mining Certification Practice Test