Certified Six Sigma Black Belt Exam Process Capability Analysis

Question 1

What does the Cp index measure in process capability analysis?

Accepted Answer

Process spread relative to specification width

Answer

Process centering relative to specification limits

Answer

Process mean shift over time

Answer

Number of defects per million opportunities

Question 2

A process has Cp = 1.5 and Cpk = 0.8. What does this indicate?

Accepted Answer

The process has sufficient spread but is significantly off-center

Answer

The process is centered and fully capable

Answer

The process is incapable due to excessive variation

Answer

Both indices confirm the process is capable

Question 3

What is the standard minimum acceptable Cpk value for a process to be considered 'capable' in most Six Sigma guidelines?

Accepted Answer

1.33

Answer

1.00

Answer

1.67

Answer

2.00

Question 4

Which capability index accounts for BOTH process spread AND centering simultaneously?

Accepted Answer

Cpk

Answer

Cp

Answer

Pp

Answer

Cpm (Taguchi index only)

Question 5

What is the key difference between Cpk and Ppk?

Accepted Answer

Cpk uses within-subgroup (short-term) variation; Ppk uses total (long-term) variation

Answer

Cpk uses total (long-term) variation; Ppk uses within-subgroup variation

Answer

They are mathematically identical measures

Answer

Cpk applies to continuous data; Ppk applies to attribute data

Question 6

When Cp equals Cpk for a process, what does this tell you about the process?

Accepted Answer

The process mean is exactly centered between the specification limits

Answer

The process has excessive variation

Answer

The process is out of statistical control

Answer

The specification limits are too wide

Question 7

Using the relationship Z = 3 × Cpk, what sigma level corresponds to a Cpk of 1.33?

Accepted Answer

4 sigma

Answer

3 sigma

Answer

5 sigma

Answer

6 sigma