Control chart: Xbar and S chart with large subgroup size unable to extract or calculate limits

Question

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 chart below). Does anyone have suggestions for how to do this?

Thanks!

shampton82 · Answer

I think this will get you what you are after

Byron_JMP · Answer

Since you aren't really using a control chart, but a Level Jennings chart which uses the overall variation of the subgroup rather than the between subgroup, you could just use the tabulate function to calculate the standard deviation for each subgroup and go from there.

BTW, using standard deviation control limits is a good way to Never see anything out of control

Abby_Collins14 · Answer

Thanks! Is there a way to pull the moving control limits? That is what I am after