What is an "X-Rs" Control Chart?


Involved In Discussions
Can someone tell me what is an "X-Rs" control chart? Is it the same thing as an Individuals and Moving Range (I-MR) chart?

If it's not the same, what is it, and how does it differ from an X-Bar & R chart?

Thank you!!

Steve Prevette

Deming Disciple
Super Moderator
It would help to know where the reference to X-Rs came from. There is also the possibility it refers to a sigma chart . . .


Involved In Discussions
I don't think it refers to a sigma chart...It came from a bad Japanese to English translation; here it is in context:

"X(-bar)-Rs is used for the same purpose as the Xbar -R Control Chart, but used for control with a piece of sample. When plural samplings are difficult in the group (e.g., destructive testing, much time needed for measurement, etc.) X(-bar)- Rs Control Chart is used."

And then later: "How many data is in the group? One => Use X(-bar)-Rs Control Chart."

I feel like it is sort of referring to an I-MR chart, but I'm no SPC expert, so I was wondering if an X(-bar)-Rs chart is one I haven't heard of, or if it's an old way of referring to an I-MR chart...
Top Bottom