Process control charts are tools used to evaluate whether a manufacturing process is in a state of statistical control. When an analysis of the charts indicates that the process is presently under control i.e. the process is in a stable state with any present variation originating from source inherent to the process, no changes to the control parameters are desired. In such situations, data generated by the process can be used to make future predictions about the process.
If the process control chart indicates that the process is out of control, an analysis of the chart is carried out to find out the causes of the variation and corrective actions are thereafter taken to avoid adverse performance.
Control chart is one among the seven basic tools of quality control. They are mostly used for time series data but they can also be used for data that shows logical comparability.