Lean Six Sigma Black Belt Certification Measure Phase: Data Analysis 2

Question 1

A process engineer notices that a control chart shows 8 consecutive points on one side of the centerline. What does this pattern indicate?

Accepted Answer

A special cause shift in the process mean

Answer

Eight consecutive points on one side of the centerline is a Western Electric Rule violation indicating a special cause—likely a sustained shift in the process mean.

Question 2

Which measure best describes the spread of the middle 50% of a data distribution?

Accepted Answer

Interquartile range (IQR)

Answer

The interquartile range (IQR) is the difference between the 75th and 25th percentiles, capturing the spread of the central 50% of data.

Question 3

In regression analysis, what does a residual represent?

Accepted Answer

The difference between observed and predicted values

Answer

A residual is the difference between an observed data value and the value predicted by the regression model.

Question 4

A Black Belt wants to compare the variance of two independent processes. Which statistical test is most appropriate?

Accepted Answer

F-test (Levene's or Bartlett's test)

Answer

The F-test (or Levene's/Bartlett's test) is used to compare the variances of two or more independent populations.

Question 5

What is the primary purpose of a multi-vari chart in the Measure phase?

Accepted Answer

To identify the largest source of variation among positional, cyclical, and temporal families

Answer

A multi-vari chart graphically separates and compares positional, cyclical, and temporal sources of variation to identify the dominant family.

Lean Six Sigma Black Belt Certification Practice Test

Lean Six Sigma Black Belt Certification Practice Test

Lean Six Sigma Black Belt Certification Measure Phase: Data Analysis 2