Control Charts Definition

Control charts are statistical tools that are used to monitor, control, and improve process quality. They are also known as Shewhart charts or process-behavior charts.

Control charts are based on statistical sampling of data, and they use upper and lower control limits (UCL and LCL) to signal when a process is out of control. Control charts can be used to monitor any type of quality characteristic, including but not limited to:

– Measurement data (e.g., length, width, thickness)

– Count data (e.g., number of defects per item)

– Percentage data (e.g., percent defective items)

When using control charts, it is important to remember that they are designed to detect small changes in the process mean or variance. Therefore, if there is a large shift in the process mean or variance, it is possible for the control chart to fail to detect this change.