Hello. I have been working with SPC Xbar-R charts, for measurements samples sizes from 1 to 7 .
Now I have a situation that I am not sure how to handle: In a new process we got, there is a measurement machine that performs thickness measurements from one sample and the result we got (from 30K-10K measurements) are Average, Max, Min.
I was asked to use SPC to keep track of the process performance using this three data. I am a little bit confused since the sample from I got the three statistics (Avg, max and Min) is really big so I cannot apply the typical SPC ideas.
First, I tried to use this three data for a Xbar-R chart, but it is clearly wrong since the sample I am using (3 data) comes from a bigger sample (10K-30K). I was thinking to use Xbar-S chart, but I am afraid it will be the same problem.
Thank you very much in advance.