Use I-MR Chart to monitor the mean and 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.
For example, a hospital administrator wants to determine whether the time to perform outpatient hernia surgery is stable and whether the variation in surgery times is stable. Because the data are not collected in subgroups, the administrator uses an I-MR chart to monitor the mean and variation of the surgery times.
Where to find this control chart
To create an I-MR chart, choose Stat > Control Charts > Variables Charts for Individuals > I-MR.