DSE Knowledge 2

Question 1

Which probability distribution is most appropriate for modeling the number of events occurring in a fixed time interval?

Accepted Answer

Poisson distribution

Answer

The Poisson distribution models the count of independent events occurring in a fixed interval of time or space.

Question 2

What does the term 'bias-variance tradeoff' describe in machine learning?

Accepted Answer

The tension between underfitting (high bias) and overfitting (high variance)

Answer

Bias-variance tradeoff refers to the tension between a model's error due to oversimplification (bias) and its sensitivity to training data fluctuations (variance).

Question 3

In SQL, what does a LEFT JOIN return?

Accepted Answer

All rows from the left table and matching rows from the right

Answer

A LEFT JOIN returns all rows from the left table and the matched rows from the right table; unmatched right-table rows appear as NULL.

Question 4

What is the purpose of cross-validation in model evaluation?

Accepted Answer

To estimate model performance on unseen data using multiple train/test splits

Answer

Cross-validation repeatedly splits data into training and validation sets to produce a more reliable estimate of generalization performance.

Question 5

Which measure of central tendency is most resistant to outliers?

Accepted Answer

Median

Answer

The median is resistant to outliers because it depends only on the middle value(s), not the magnitude of extreme values.

DSE - Data Science Practice Test

DSE - Data Science Practice Test

DSE Knowledge 2