Lean Six Sigma Yellow Belt Certification Statistical Thinking and Variation

Question 1

What are the two main types of process variation recognized in Six Sigma?

Accepted Answer

Common cause and special cause variation

Answer

Controlled and uncontrolled variation

Answer

Internal and external variation

Answer

Random and systematic variation

Question 2

Which of the following is an example of special cause variation?

Accepted Answer

A damaged cutting tool producing oversized parts

Answer

Minor fluctuations in machine output due to normal wear

Answer

Slight temperature differences in a controlled environment

Answer

Random measurement differences within specification limits

Question 3

Walter Shewhart's primary contribution to statistical thinking was developing a method to:

Accepted Answer

Distinguish between common and special cause variation

Answer

Eliminate all variation from manufacturing processes

Answer

Calculate the cost of poor quality

Answer

Set customer specification limits

Question 4

A process that exhibits only common cause variation is described as:

Accepted Answer

In a state of statistical control

Answer

Incapable of meeting specifications

Answer

Out of statistical control

Answer

Exhibiting assignable cause variation

Question 5

Statistical thinking in Six Sigma is best described as:

Accepted Answer

Recognizing that variation exists in all processes and can be measured and reduced

Answer

Applying complex formulas to every business decision

Answer

Using statistics to prove processes are defect-free

Answer

Eliminating the need for qualitative analysis

Question 6

What is the appropriate response when a process displays only common cause variation but does not meet customer specifications?

Accepted Answer

Redesign or fundamentally change the process system

Answer

React to individual defective parts by adjusting the machine

Answer

Investigate and remove the special cause immediately

Answer

Widen the specification limits to accept current output

Question 7

In statistical thinking, the term 'noise' refers to:

Accepted Answer

Common cause variation inherent to the process

Answer

Loud machinery interfering with measurements

Answer

Special cause variation that disrupts production

Answer

Customer complaints about product consistency