Xbar-R Chart better than Xbar-S Chart when the subgroup size is small - Why?

B

Bill Pflanz

#11
... the reality is that Control Charts are not and never were intended to provide accurate and precise point estimates of the process performance.
in short: it doesn't matter. use one of them. Shewharts' book was entitled "the economic control of quality", not the "exactly precise accurate determination of exactly what is going on with infinite confidence in the results"
I like your response. :)
 
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Bev D

Heretical Statistician
Staff member
Super Moderator
#12
Interestingly, the article only made a connection between the control chart constants and the normal distribution.
Bob - I was referring to the WIKI articles not the NIST document you commented on. The wiki articles posted by HARRY are incorrect and do make the incorrect claims as I wrote.
 

bobdoering

Stop X-bar/R Madness!!
Trusted Information Resource
#13
Bob - I was referring to the WIKI articles not the NIST document you commented on. The wiki articles posted by HARRY are incorrect and do make the incorrect claims as I wrote.
Thanks for the clarification...but you know I had to have some fun with this. :tg: Besides, it was more for others benefit...not much you haven't already heard from me!
 
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