In quality control, what is the purpose of using a control chart?

The purpose of using a control chart in quality control is to visually monitor process variability over time. Control charts are essential tools for evaluating the consistency of processes by plotting data points over a specified time period. They provide a clear visual representation of trends, patterns, and variations in the process being monitored, which helps in identifying when a process is in control or when it may be going out of control.

By utilizing control charts, organizations can determine the stability of their processes, identify special causes of variation, and take corrective actions when necessary. This visual monitoring aids in making informed decisions to improve the quality of products or services, ensuring that they meet the required standards consistently over time.

While the other options might be relevant in different contexts, they do not reflect the core purpose of a control chart, which is focused on monitoring process variability rather than cost, compliance, or waste reduction.