Lean Six Sigma Green Belt Certification Basic Statistical Tools 3

Question 1

In hypothesis testing, what does the p-value represent?

Accepted Answer

The probability of observing results as extreme as the sample if the null hypothesis is true

Answer

The p-value is the probability of obtaining the observed data (or more extreme) assuming the null hypothesis is true.

Question 2

A Type II error in hypothesis testing occurs when you:

Accepted Answer

Fail to reject a false null hypothesis

Answer

A Type II error (β) means failing to detect a real effect — accepting H₀ when it is actually false.

Question 3

What does a Cpk value of 1.33 indicate about a process?

Accepted Answer

The process is capable and has some margin relative to the nearest specification limit

Answer

Cpk = 1.33 is the traditional minimum target, indicating the process mean is at least 4σ from the nearest spec limit.

Question 4

Which statistical test compares the means of exactly two independent groups?

Accepted Answer

Two-sample t-test

Answer

A two-sample t-test compares the means of two independent groups to determine if they differ significantly.

Question 5

What is the interquartile range (IQR) used to measure?

Accepted Answer

The spread of the middle 50% of data

Answer

IQR = Q3 − Q1, capturing the spread of the central 50% of the data and resisting outlier influence.

Lean Six Sigma Green Belt Certification Practice Test