Re: Gage R&R Sample Question
Gage R&R is one facet of measurement system analysis. Clearly, it is difficult enough to have a tool that already includes environment, gage, operator and part. To add measurement error to this tool will mask the answer you are trying to get from the tool: Is this gage an adequate gage for the measurement? Very few gages are adequate when used incorrectly - so I am not inclined to throw that into this particular tool's usage.
I understand your point. If you chose to do a gage R&R using the tool correctly and a gage r&r using the tool incorrectly to prove the point, it would be an interesting academic exercise. Unfortunately, most of the people that need that training are the quality professionals that do not recognize such issues as measuring one diameter out of an infinite number of diameters is not an adequate way to describe a circular feature - not the operators they are training.
But, to burden gage decisions on incorrect measurement is certainly not a fair assessment of the gage's capability. And, if the gage fails gage R&R because of that, I would be suspicious that one would recognize that the measurement error - not the other facets of the gage error - is what would need to be corrected. A more accurate gage would never resolve that problem!
I am not disagreeing that you should understand the difference, but never forget it is called MEASUREMENT systems analysis, not gauge analysis.
You should purposely separate each of the components of the measurement system to fully understand them. The part that I strongly disagree about is limiting the effect of the within part variation in the situation where it is not ALSO controlled during normal measurement. If this is not made clear, the person will control variation for the purpose of the study, get an acceptable %SV, then promptly allow the operators to measure however they will. This is only kidding yourself.
But, to burden gage decisions on incorrect measurement is certainly not a fair assessment of the gage's capability. And, if the gage fails gage R&R because of that, I would be suspicious that one would recognize that the measurement error - not the other facets of the gage error - is what would need to be corrected. A more accurate gage would never resolve that problem!