In Reply to Parent Post by Coleman Donnelly
Anyone else care to chime in on this?
In order to answer effectively I woudl want to know what you are lookign for (I would give different input based on your answer)
do you want to truly improve your process?
are you only interested in submitting the appropriate paperwork to your customer and not raising any questions from them?
whether your parts are in tolerance or out of tolerance has no bearing on the validity of the assessment of the measurement system. Most of the time the more variation you have the more informative the study is, particularly if your system has measuremetn error that is variable dependign on the actaul value...by the way jsut to stir the pot some more, 10 pieces is really too small: we're trying to estimate a standard deviation with subgroups of 2-3 pieces...30 subgroups is a better sample size for this.
Your customer may feel differently: some require you to have out of spec parts to assess your ability to detect our of tolerance parts; some don't want out of tolerance parts in teh study becuase they - wrongly - interpret their presence as an indication that your process is not capable and you will ship them nonconforming parts.