Certified Six Sigma Black Belt Exam Process Capability Analysis 3

Question 1

The standard '1.5 sigma shift' used in Six Sigma calculations accounts for which source of variation?

Accepted Answer

Typical long-term drift of the process mean over time

Answer

Measurement system error

Answer

Operator-to-operator variation within a single shift

Answer

Seasonal raw material variation only

Question 2

What is the recommended minimum sample size for a reliable process capability study?

Accepted Answer

Approximately 100 data points (or 30+ subgroups of 3–5)

Answer

20 data points

Answer

50 data points

Answer

500 data points minimum

Question 3

If a process has Cp = 2.0 and is perfectly centered, what sigma level does this represent?

Accepted Answer

6 sigma

Answer

4 sigma

Answer

5 sigma

Answer

8 sigma

Question 4

In Six Sigma terminology, 'first pass yield' (FPY) is best defined as:

Accepted Answer

Percentage of units completing a process step without any defect the first time

Answer

Percentage of products passing final inspection including reworked units

Answer

Throughput rate of the production line per hour

Answer

Ratio of value-added time to total cycle time

Question 5

What is the fundamental difference between a control limit and a specification limit?

Accepted Answer

Control limits are statistically derived from process data; specification limits are set by customer or engineering requirements

Answer

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

Answer

They serve the same function and can be used interchangeably

Answer

Control limits apply only to attribute data; specification limits apply only to variable data

Question 6

A Black Belt finds Cp = 1.8 and Cpk = 0.6 for a critical process. What is the highest-priority corrective action?

Accepted Answer

Center the process mean within the specification limits

Answer

Implement process improvements to reduce standard deviation

Answer

Negotiate wider specification limits with the customer

Answer

Increase the measurement frequency to gather more data

Question 7

Which approach is valid for performing capability analysis when process data follows an exponential distribution?

Accepted Answer

Transform the data (e.g., Box-Cox) to achieve normality, or use non-normal distribution-fitting methods

Answer

Apply standard Cp/Cpk directly since sample size corrects for non-normality

Answer

Use only DPMO without any capability index

Answer

Replace capability analysis with a regression model