The DMAIC (Define, Measure, Analyze, Improve, Control) process is a data-driven quality strategy used to improve processes12. In the context of a DMAIC project, when you want to demonstrate that change has occurred over time and the process has limited variation, a control chart is the most appropriate tool.

A control chart is a graph used to study how a process changes over time. It is particularly useful in the Control phase of the DMAIC process. The chart is used to monitor the process and ensure it remains stable. Data points are plotted in time order in a control chart and a centerline is calculated. The centerline is the average value of the metric you are charting. A control chartalways has a central line for the average, an upper line for the upper control limit, and a lower line for the lower controllimit. These lines are determined from historical data. By comparing current data to these lines, you can draw conclusions about whether the process variation is consistent (in control) or is unpredictable (out of control, affected by special causes of variation).