Control chart: Xbar and S chart with large subgroup size unable to extract or calculate limits
I am working on building Xbar and S chart to monitor a process where we observe the data (Y) every 1 minute across multiple runs. I wanted a chart where I have the control limits be the average of each time point across runs, which I believe the Xbar and S chart is doing. However, the actual LCL and UCL limits are not showing up, and I don't know how to extract them from the plot (see example char...