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 Pearson correlation of -0.92 indicates a strong negative linear relationship, meaning as one variable increases, the other decreases proportionally.

Question 2

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

Accepted Answer

Normal distribution of independent variables

Answer

OLS regression requires normality of residuals, not normality of the independent variables themselves.

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

Since the p-value (0.03) is less than the significance level (0.05), we reject the null hypothesis.

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

Cross-validation estimates a model's generalization performance by repeatedly training and testing on different subsets of the data.

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

When the mean is greater than the median, which is greater than the mode, the distribution is positively (right) skewed.

Data Science Practice Test

Data Science Practice Test

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