Actions Taken to Improve the Process. Process improvement is the primary
objective of statistical process control. The application of control charts will give information
on two key aspects of the process: statistical control and capability. Figure 7.27
shows the possible states in which the process may exist with respect to these two issues.
Technically speaking, the capability of a process cannot be adequately assessed until
statistical control has been established, but we will use a less precise definition of capability
that is just a qualitative assessment of whether or not the level of nonconforming
units produced is low enough to warrant no immediate additional effort to further improve
the process.