What is the purpose of a control chart?

The purpose of a control chart is to monitor process variability and control processes. This tool is essential in the field of quality management and continuous improvement, particularly within Lean Six Sigma methodologies. Control charts are graphical representations that help in understanding how a process behaves over time by plotting data points against time and indicating upper and lower control limits.

By using control charts, organizations can identify variations in a process—distinguishing between common cause variations, which are inherent to the process, and special cause variations, which are due to specific, identifiable factors. This distinction is critical for maintaining consistency and quality within processes. When data points fall outside of the control limits, it signals that a special cause may be affecting the process, prompting further investigation and potential corrective actions.

In summary, control charts are pivotal in helping teams maintain control over processes, ensuring they remain stable and predictable, which ultimately leads to higher quality outputs and reduced variability.