Use Moving Range
Chart to monitor the variation of your process when you have continuous data that are individual observations not in subgroups. Use this control chart to monitor process stability over time so that you can identify and correct instabilities in a process.
A hospital administrator wants to monitor whether the variation in surgery times is stable. Because the data are not collected in subgroups, the administrator uses a moving range chart to monitor the variation of the surgery times.
The points vary randomly around the center line and are within the control limits. No trends or patterns are present. The variation in times are stable.
Where to find this control chart
To create a moving range chart, choose Stat > Control Charts > Variables Charts for Individuals > Moving Range.
When to use an alternate control chart
If you can collect data in subgroups, use R Chart or S Chart.
If your data are counts of defectives or defects, use an attribute control chart, such as P Chart or U Chart.
