Control charts are useful for evaluating the stability of a process. They are used to study the variation of the mean, range, and standard deviation for a controlled sample. Each control chart is graphically represented as a diagram.

In a very simple way, it is seen when corrective measures are needed and whether there has been an improvement in a certain observed time interval.

The use of control charts in monitoring and measuring a process is called Statistical Process Control (SPC).

The preparation of control charts is based on statistics and is used either for diagnosing the stability of a process, or for controlling the process, or for confirming that the process is operating under the required conditions. Control charts are good for early detection of errors.

Image credit: By DanielPenfield - Own work, CC BY-SA 3.0