Year
1995
Abstract
The zone control chart is a simple, easy to learn statistical process control (SPC) tool that can be applied to any process where the data are normally distributed. Several Shewhart runs rules are incorporated into a simple scoring system, with a single rule to determine when a process is out of control. Zone charts have average run lengths (ARLs) for detecting shifts in the process mean which, for most cases, are uniformly better than the standard control charts. This paper presents the simplified methodology behind the zone control chart.