Data Science Supervised Learning Algorithms 2

Question 1

In a decision tree, what does a higher Gini impurity at a node indicate?

Accepted Answer

The classes are more mixed at that node

Answer

Gini impurity increases as class distribution within a node becomes more mixed.

Question 2

Which supervised algorithm is most prone to overfitting if grown without depth limits?

Accepted Answer

An unpruned decision tree

Answer

A fully grown unpruned tree can memorize training data, causing overfitting.

Question 3

What is the primary purpose of the kernel trick in support vector machines?

Accepted Answer

To enable linear separation in a higher-dimensional space without explicit mapping

Answer

The kernel trick computes inner products in a higher-dimensional space implicitly, allowing nonlinear separation.

Question 4

In logistic regression, what does the sigmoid function output represent?

Accepted Answer

A probability between 0 and 1

Answer

The sigmoid maps the linear combination of inputs to a probability between 0 and 1.

Question 5

Why does k-nearest neighbors require feature scaling?

Accepted Answer

Distance calculations are dominated by large-range features

Answer

Unscaled features with larger ranges disproportionately influence the distance metric.

Data Science Practice Test