# How to interpret the average R bar Value shown in the R Chart

L

#### lello_1983

Hi,
First of all I would like to thank you for the great community you have here!!

I just need a clarification about the interpretation of Gage R&R results, used to evaluate the adequacy of a measurement system;
In particular, I would like to better understand how to interpret the average Rbar value shown in the R chart;

How can I use the R value of the R chart in order to understand if the measurement system is able to discriminate between different parts?

#### AMIT BALLAL

Trusted Information Resource
how to interpret the average Rbar value shown in the R chart:

Lower the R is better, which would show variability of your measurement system. lower the R, lower the GRR- which is expected. Apply control chart rules to check whether the measurement process is in control (Identify special cause and eliminate).

measurement system is able to discriminate between different parts:

nDc would tell you whether measurement system is able to discriminate.

Thanks,
Amit

#### Bev D

##### Heretical Statistician
Staff member
Super Moderator
To add to Amit's response: the Rbar chart shows the actual range of the repeated measurements of each unit. So the UCL would be roughly the largest expected difference between repeat measurements and the average Range would be the average difference. The control chart itself is intended to detect if any of the repeated measurements were suspect of a miss-measurement or mis entry. This would be indicated by an out-of-control point.

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