What is the primary purpose of a control chart?

A control chart serves multiple important functions in quality management, which justifies the choice of the option that encompasses all of them. Firstly, its primary purpose is to monitor the degree of variation in a process. By plotting data points over time, control charts provide a visual representation of fluctuations, helping organizations understand and quantify the variability inherent in their processes.

Additionally, control charts are used to judge whether a process is statistically in control. This involves analyzing the plotted data against predetermined control limits to identify any patterns or trends that may suggest the process is deviating from expected performance. If data points fall within these limits and show no non-random patterns, the process can be considered statistically stable.

Furthermore, control charts aid in finding and correcting problems within an ongoing process. When variations exceed the control limits or display unusual patterns, it signals that something may be wrong, prompting an investigation into potential causes and corrective actions.

By encompassing all these critical functions—monitoring variation, assessing statistical control, and identifying areas for improvement—the comprehensive approach justifies the correctness of the selected answer.