Lean Six Sigma Green Belt Certification Measure Phase and Statistics 4

Question 1

A normal distribution has 99.73% of data within how many standard deviations of the mean?

Accepted Answer

3

Answer

The empirical rule states that 99.73% of data falls within ±3 standard deviations of the mean in a normal distribution.

Question 2

What does the acronym DPMO stand for in Six Sigma?

Accepted Answer

Defects Per Million Opportunities

Answer

DPMO stands for Defects Per Million Opportunities and is the standard metric used to calculate sigma level.

Question 3

In a Gage R&R study expressed as %Study Variation, what threshold is typically considered acceptable for measurement systems?

Accepted Answer

Less than 10%

Answer

A %Study Variation below 10% indicates an acceptable measurement system; 10-30% may be acceptable depending on context.

Question 4

Which distribution is most appropriate for modeling the number of defects per unit when defects are rare and independent?

Accepted Answer

Poisson distribution

Answer

The Poisson distribution models the number of rare, independent events occurring in a fixed interval of time or space.

Question 5

What is the difference between accuracy and precision in measurement systems?

Accepted Answer

Accuracy is closeness to true value; precision is consistency of repeated measurements

Answer

Accuracy refers to how close a measurement is to the true value (low bias), while precision refers to how consistently measurements repeat.

Lean Six Sigma Green Belt Certification Practice Test