If Cp and Cpk are both 2.0, what does this indicate about process capability?

• A. The process is not capable.
• B. The process is moderately capable.
• C. The process is low centering, but capable.
• D. The process is highly capable with respect to specification limits.

Answer: (D)

Cp and Cpk quantify how well a process fits within specification limits given its variability. Cp looks at potential capability by comparing the spread of the process to the tolerance width, while Cpk accounts for how centered the process is within those limits and reflects actual performance. When both indices are 2.0, it means the process spread is very small relative to the tolerance and the mean is centered between the limits, so measurements stay well inside spec on both sides. This indicates a highly capable process with respect to specification limits and a very low likelihood of defects due to natural variation.