Determining if a process is stable is important to
understand if improvements have been sustained and to
predict future performance which will impact decisionmaking.
To determine if a process or system is in a stable
state, a Shewhart (control) chart is needed.4 5 13 In using
run charts, we recommend avoiding the terms special
and common cause and stable or unstable, reserving
their use for Shewhart (control) charts.