Certified Six Sigma Black Belt Statistical Process Control (SPC) Questions and Answers

Question 1

A Black Belt is analyzing process data where the number of surface blemishes is counted on manufactured panels.
The size of the panels inspected varies from one subgroup to the next.
Which type of control chart is most appropriate for monitoring this process?

Accepted Answer

u-chart

Answer

p-chart

Answer

c-chart

Answer

np-chart

Question 2

While reviewing a control chart, a quality analyst observes seven consecutive data points trending downwards. What does this pattern most likely indicate?

Accepted Answer

A special cause of variation is present, suggesting a gradual process shift.

Answer

The process has become more stable and predictable.

Answer

The measurement system has an issue with reproducibility.

Answer

This is common cause variation and no action is required.

Question 3

A process capability analysis yields a Cp value of 1.67 and a Cpk value of 0.85. Which of the following is the most accurate interpretation of these results?

Accepted Answer

The process is not centered within the specification limits.

Answer

The process variation is too large relative to the specification limits.

Answer

The measurement system is not capable of assessing the process.

Answer

The process is both capable and centered.

Question 4

A manufacturing process producing specialty bolts is monitored by taking a sample of 5 consecutive bolts every hour. This data is then plotted on an X-bar & R chart. This method of sampling is an application of which fundamental SPC concept?

Accepted Answer

Rational Subgrouping

Answer

Process Centering

Answer

Attribute Data Collection

Answer

Random Sampling

Question 5

A chemical process has a long cycle time, and a critical quality characteristic can only be measured once when each batch is completed. Which control chart is the most suitable for monitoring this process characteristic?

Accepted Answer

I-MR (Individuals and Moving Range) chart

Answer

p-chart

Answer

X-bar and S chart

Answer

c-chart

Question 6

Which of the following statements best distinguishes between common cause and special cause variation?

Accepted Answer

Common cause variation is predictable and inherent to the process, while special cause variation is unpredictable and arises from specific, identifiable events.

Answer

Special cause variation is always undesirable and must be eliminated, while common cause variation is always acceptable.

Answer

Common cause variation is identified when a point falls outside the control limits, while special cause variation is the noise within the limits.

Answer

Reducing common cause variation is the responsibility of operators, while addressing special cause variation is the responsibility of management.

A Black Belt is analyzing process data where the number of surface blemishes is counted on manufactured panels.The size of the panels inspected varies from one subgroup to the next.Which type of control chart is most appropriate for monitoring this process?

A Black Belt is analyzing process data where the number of surface blemishes is counted on manufactured panels.
The size of the panels inspected varies from one subgroup to the next.
Which type of control chart is most appropriate for monitoring this process?