Data Science Data Science Statistical Concepts and Analysis Questions and Answers 2

Question 1

A data scientist observes that two variables have a Pearson correlation coefficient of -0.92. What does this indicate?

Accepted Answer

A strong negative linear relationship

Answer

A strong positive linear relationship

Answer

No linear relationship

Answer

A weak negative linear relationship

Question 2

Which assumption is NOT required for a valid ordinary least squares (OLS) linear regression?

Accepted Answer

Normal distribution of independent variables

Answer

Linearity between predictors and response

Answer

Homoscedasticity of residuals

Answer

Independence of observations

Question 3

In a hypothesis test, a p-value of 0.03 with a significance level of 0.05 leads to which conclusion?

Accepted Answer

Reject the null hypothesis

Answer

Fail to reject the null hypothesis

Answer

Accept the alternative hypothesis as proven

Answer

The test is inconclusive

Question 4

What is the primary purpose of cross-validation in predictive modeling?

Accepted Answer

To estimate how well a model generalizes to unseen data

Answer

To increase the training dataset size

Answer

To eliminate all bias from the model

Answer

To select the features with highest correlation

Question 5

A dataset has a mean of 50, a median of 42, and a mode of 38. What type of skewness does this distribution exhibit?

Accepted Answer

Positive skew

Answer

Negative skew

Answer

No skew

Answer

Bimodal distribution

Question 6

Which metric is most appropriate for evaluating a classification model when the dataset has a 95:5 class imbalance?

Accepted Answer

F1 Score

Answer

Accuracy

Answer

R-squared

Answer

Mean Absolute Error