A control chart is a graph that is used to study how a process changes over time. Data points are plotted in time order. A control chart often displays a CL for the average value, a UCL line, and a LCL line to differentiate acceptable values from anomalies. These control limits are determined based on 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).
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