Data Science Statistical Concepts and Analysis 4

Question 1

Which statement about correlation and causation is correct?

Accepted Answer

Correlation does not imply causation

Answer

Two variables can move together due to confounders or chance without one causing the other.

Question 2

The power of a statistical test is the probability of:

Accepted Answer

Correctly rejecting a false null hypothesis

Answer

Power equals 1 minus the Type II error rate—the chance of detecting a real effect.

Question 3

Which test is most appropriate for comparing the means of two independent groups?

Accepted Answer

Independent samples t-test

Answer

An independent samples t-test compares means between two separate groups.

Question 4

A z-score of 2.0 tells you that a value is:

Accepted Answer

Two standard deviations above the mean

Answer

A z-score expresses how many standard deviations a value lies from the mean.

Question 5

Which scenario describes selection bias?

Accepted Answer

A survey sample systematically excludes part of the target population

Answer

Selection bias arises when the sample is not representative because certain groups are systematically over- or under-included.

Data Science Practice Test