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

Strong correlation proves causation

Answer

Correlation and causation are identical

Answer

Causation requires no correlation

Question 2

The power of a statistical test is the probability of:

Accepted Answer

Correctly rejecting a false null hypothesis

Answer

Rejecting a true null hypothesis

Answer

Accepting a false null hypothesis

Answer

Making no errors at all

Question 3

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

Accepted Answer

Independent samples t-test

Answer

Chi-square test

Answer

Pearson correlation

Answer

One-way ANOVA with one group

Question 4

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

Accepted Answer

Two standard deviations above the mean

Answer

Twice the mean

Answer

At the 2nd percentile

Answer

Two units above the median

Question 5

Which scenario describes selection bias?

Accepted Answer

A survey sample systematically excludes part of the target population

Answer

Random measurement noise in instruments

Answer

Rounding errors in calculations

Answer

A perfectly representative random sample

Question 6

When a dataset is heavily skewed, which transformation is commonly used to reduce skewness?

Accepted Answer

Log transformation

Answer

Adding a constant to all values

Answer

Multiplying by the mean

Answer

Reversing the order of data

Question 7

What is the purpose of a chi-square test of independence?

Accepted Answer

To assess whether two categorical variables are associated

Answer

To compare two means

Answer

To measure linear correlation

Answer

To estimate a population mean