Lean Six Sigma Yellow Belt Certification Statistical Thinking and Variation 2

Question 1

Control charts have control limits set at ±3 standard deviations from the mean because:

Accepted Answer

This range captures approximately 99.73% of common cause variation

Answer

It is a regulatory requirement in manufacturing

Answer

Customer specifications typically fall at ±3 sigma

Answer

Three is a convenient round number for calculations

Question 2

What is the key difference between control limits and specification limits?

Accepted Answer

Control limits are calculated from process data; specification limits are set by customer requirements

Answer

Control limits are wider; specification limits are narrower

Answer

Control limits are set by customers; specification limits are calculated from process data

Answer

They are different names for the same concept

Question 3

A point falling outside the control limits on a control chart most likely indicates:

Accepted Answer

A special cause of variation has occurred

Answer

The process is performing exceptionally well

Answer

Common cause variation is present

Answer

A specification limit has been violated

Question 4

A histogram is used in Six Sigma primarily to:

Accepted Answer

Display the frequency distribution of process data

Answer

Track data over time and identify trends

Answer

Show the relationship between two variables

Answer

Rank defect categories by frequency

Question 5

What does a run chart help a Yellow Belt team identify?

Accepted Answer

Trends, shifts, or patterns in process data over time

Answer

The frequency of each defect type in a process

Answer

How two process variables are related

Answer

The capability of a process relative to specifications

Question 6

If a control chart shows a consistent upward trend of seven consecutive points, this is:

Accepted Answer

A signal of a special cause that should be investigated

Answer

Normal common cause variation that requires no action

Answer

Proof that the process is meeting specifications

Answer

An indication that control limits should be recalculated

Question 7

The Voice of the Process (VOP) represents:

Accepted Answer

What the process is actually capable of delivering based on its own performance data

Answer

Customer requirements expressed in measurable terms

Answer

Management's targets for process improvement

Answer

Employee feedback on process design