Definition of X-Bar and R Charts:
This set of two charts is the most commonly used statistical process control procedure. Used to monitor process behavior and outcome overtime.
X-Bar and R charts draw a control chart for subgroup means and a control chart for subgroup ranges in one graphic. Interpreting both charts together allows you to track both process center and process variation and detect the presence of special causes. Generally, a user focuses on the range portion of the chart first, confirming that the process is in control. Finally, the user focuses on the average chart, looking for special cause there.« Back to Dictionary Index