Hi All
I have a situation where I am interested in computing an SPC chart for the median and was wondering if anyone has the formula for the control limits or a reference containing the formula?
Here are the details. I have k subgroup medians where each subgroup is of size n_i (i=1...k). I plot these sugroup medians and would like to have a formula for computing the upper and lower control limits. In the references I have , there are tables for n_i <= 10 , however in my case n_i ranges from 100 to 1000.
Also how about control limits for other percentiles, can the same fomulae be used?
Any help on this matter would be really appreciated
Best Regards,
Mary.
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