Six Sigma Green Belt Certification Practice Exam

Two processes, A and B, have been examined. Process A's capability ratio (Cr) is 0.85 while process B's process capability (Cp) is also 0.85. Which statement is true about these processes?

1. Process A is capable, process B is capable

2. Process A is capable, process B is incapable

3. Process A is incapable, process B is capable

4. Process A is incapable, process B is incapable

The correct answer is: Process A is capable, process B is incapable

In this scenario, both processes A and B have a capability ratio (Cr) and process capability (Cp) of 0.85. To understand the implications of this value, it is essential to recognize that a capability ratio (Cr) is a measure that accounts for the actual process performance, including the process mean and variation, in relation to the specified limits. When Cr is less than 1, it indicates that the process is performing below the desired specification limits, suggesting that the process is not capable of meeting customer requirements consistently. In this case, a Cr of 0.85 means that Process A is not capable of producing outputs within the specified limits reliably. On the other hand, process capability (Cp) measures the potential of a process to produce outputs that meet specifications, disregarding the actual process performance. A Cp value of 0.85 also indicates that the process may not effectively produce products that consistently meet the specifications if the process mean is not centered within the specification limits. Since Cr represents the actual performance incorporating process variation, while Cp represents theoretical capability without considering shifts in the mean, having both processes at a value of 0.85 signifies that Process A’s actual performance is below the acceptable threshold, leading to the conclusion