Machine Learning Classification 3

Question 1

Which technique is used to handle class imbalance by creating synthetic minority class samples?

Accepted Answer

SMOTE (Synthetic Minority Over-sampling Technique)

Answer

SMOTE generates new synthetic samples by interpolating between existing minority class examples and their nearest neighbors.

Question 2

In logistic regression, what is the role of the sigmoid function?

Accepted Answer

It maps linear combinations of features to a probability between 0 and 1

Answer

The sigmoid function squashes the linear combination of inputs into the range (0, 1), allowing logistic regression to output class probabilities.

Question 3

What does the ROC curve plot?

Accepted Answer

True Positive Rate vs. False Positive Rate at various classification thresholds

Answer

The ROC curve plots TPR (sensitivity) on the y-axis versus FPR (1 - specificity) on the x-axis across all possible classification thresholds.

Question 4

Which decision tree splitting criterion measures the average uncertainty weighted by each subset's size?

Accepted Answer

Gini Impurity

Answer

Gini impurity measures how often a randomly chosen element would be misclassified; weighted average across children is minimized at each split in CART.

Question 5

What is 'one-vs-rest' (OvR) strategy in multi-class classification?

Accepted Answer

Training one binary classifier per class to distinguish that class from all others combined

Answer

OvR trains N binary classifiers (one per class), each distinguishing its class from all remaining classes, then assigns the class with the highest confidence score.

Machine Learning Practice Test

Machine Learning Practice Test

Machine Learning Classification 3