Data Science Feature Engineering and Selection 2

Question 1

You apply a log transformation to a right-skewed feature containing zero values. What problem will this cause?

Accepted Answer

log(0) is undefined/negative infinity

Answer

log(0) is undefined, so a constant (e.g., log1p) must be added before transforming zeros.

Question 2

Which technique creates new features by multiplying or combining two existing features?

Accepted Answer

Interaction features

Answer

Interaction features capture combined effects by multiplying or otherwise combining existing variables.

Question 3

When applying one-hot encoding to a feature with very high cardinality, the main drawback is:

Accepted Answer

A large, sparse feature space that increases dimensionality

Answer

High-cardinality one-hot encoding produces many sparse columns, dramatically increasing dimensionality.

Question 4

Target encoding replaces a category with what value?

Accepted Answer

The mean of the target for that category

Answer

Target (mean) encoding maps each category to the average target value observed for it.

Question 5

Which scaling method is most robust to outliers?

Accepted Answer

Robust scaling using median and IQR

Answer

RobustScaler uses the median and interquartile range, making it resistant to outliers.

Data Science Practice Test