Data Science Statistical Concepts and Analysis 2

Question 1

A dataset of household incomes has a few extreme high values. Which measure of central tendency is LEAST affected by these outliers?

Accepted Answer

Median

Answer

The median is based on rank position, so extreme values do not pull it like they pull the mean.

Question 2

A p-value of 0.03 in a test with significance level 0.05 means:

Accepted Answer

Reject the null hypothesis

Answer

When the p-value is below alpha, the result is statistically significant and the null hypothesis is rejected.

Question 3

Which statement best describes the Central Limit Theorem?

Accepted Answer

The sampling distribution of the mean approaches normality as sample size grows

Answer

The CLT states the distribution of sample means tends toward normal regardless of the population shape as n increases.

Question 4

A correlation coefficient of -0.85 between two variables indicates:

Accepted Answer

A strong negative linear relationship

Answer

Values near -1 indicate a strong inverse linear association.

Question 5

What does a 95% confidence interval for a mean actually represent?

Accepted Answer

A range that would contain the true mean in 95% of repeated samples

Answer

The confidence level refers to the long-run proportion of such intervals capturing the true parameter.

Data Science Practice Test