Statistical Process Control (SPC) Resource Center

What is Process Capability?

  • Process capability compares the process output with the customer’s specification.
  • The purpose of a process capability study is to compare the process specification to the process output and determine statistically if the process can meet the customer’s specification.

A capable process is:

  • Stable and not changing.
  • Can fit within the customer’s specification with a little extra room (usually 25%) to spare.

The less variation there is in a process, the more capable it will be of meeting the customer’s specification.

Capable AND Centered

  • When using process capability as a means for measuring how well our process is producing compared to the customer’s requirements, it is not good enough to just make sure the process is capable; it must also be fairly well-centered.

A capable and centered process.