What characteristic defines an average chart?

An average chart, specifically known as an X-bar chart, is characterized by its use of the subgroup average. This type of control chart is designed to monitor the mean values of a process over time by analyzing samples or subgroups taken from that process. Each point on the chart represents the average of a specific number of measurements collected during a given time period, providing a visual representation of how the process mean behaves.

In quality management, the average chart is crucial because it helps detect shifts or trends in the process mean, allowing managers to identify when the process may be going out of control. By focusing on averages derived from sample subgroups, it can efficiently summarize the performance of the process without the noise of individual measurement variability.

This usage aligns with the goals of continuous improvement and quality control, making the average chart an essential tool in statistical process control.