UCL&LCL on Variability Chart

[#1]

Variability Gauge Chart

I am very new to JMP. Based on the chart, how is the UCL and LCL being determine? Is it based on SD? By using Vial E, the data points that have very tight SD are having the maximum UCL and LCL range, as compared to the rest.

The max. UCL and min. UCL are the same across the data, same goes to LCL. Can someone explain to me?

[#2]

These are XBar control limits.  They are the same limits you woud get when creating an XBar and S control chart in Control Chart Builder.  The formulas for the control limits can be found in the Quality and Process Methods book.  In the Control Chart Builder section under Statistical Details, you will find the formulas for X-bar and S-charts.