Control charts are used to monitor the output of a process. They are used to give timely warning of 'special causes' entering the process. They generally monitor either the process mean, the process variation or a combination of both.
Control charts have an upper and lower 'Control Limit'. A point plotting outside these limits indicates a 'special cause'. Certain other patterns of points also indicate a 'special cause'.
Pass your mouse over the image to see a point outside a control limit , indicating that the process has changed.
Control charts can be divided into two types; control charts for attributes and control charts for variables. Types of control chart include:
Other relevant topics in this glossary include: