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% Gauge R&R or Precision-to-Tolerance ratio

When reporting the Gauge R&R in version 13.1.0 the below report is available. When I open help, the below does not specify which is the % Gauge R&R number for the guidelines. 

Example of the Gauge R&R Report
Note: To generate the reduced Gauge R&R report, select File > Preferences > Platforms > Variability Chart > Reduced Gauge RR Report.
In this example, the values in the Variation column are the square roots of sums of variance components scaled by the value of k (6 in this example).
Acceptable Percent Measurement Variation shows guidelines for measurement variation, as suggested by Barrentine (1991).
Acceptable Percent Measurement Variation 
< 10%
11% to 20%
21% to 30%
marginally acceptable
> 30%
Note the following:
If you have provided a Tolerance Interval in the Enter/Verify Gauge R&R Specifications window, a % of Tolerance column appears in the Gauge R&R report. This column is computed as 100*(Variation/Tolerance). Also, a Precision-to-Tolerance ratio appears at the bottom of the report. This ratio represents the proportion of the tolerance or capability interval that is lost due to gauge variability.
If you have provided a Historical Sigma in the Enter/Verify Gauge R&R Specifications window, a % Process column appears in the Gauge R&R report. This column is defined as follows: 100*(Variation/(K*Historical Sigma)).
The Number of Distinct Categories (NDC) is defined as (1.41*(PV/RR)), rounded down to the nearest integer.
Below are my results.   If I use the 3.4% Gauge R&R then I believe my MSA is Excellant.
But if I look at the .81 Precision to Tolerance Ratio my MSA is not good as I would read this as 81%.  Which is the correct number to use for the above guidelines?


Gauge R&R (copied as Text)

Measurement Source Variation (6*StdDev) % of Tolerance which is 6*sqrt of
Repeatability (EV) 0.0779517 77.95 Equipment Variation V(Within)
Reproducibility (AV) 0.0221650 22.17 Appraiser Variation V(Technician)
Technician 0.0221650 22.17 V(Technician)
Gauge R&R (RR) 0.0810417 81.04 Measurement Variation V(Within) + V(Technician)
Part Variation (PV) 2.3527216 2352.7 Part Variation V(Part SN)
Total Variation (TV) 2.3541170 2354.1 Total Variation V(Within) + V(Technician) + V(Part SN)


6 k
3.44255 % Gauge R&R = 100*(RR/TV)
0.03445 Precision to Part Variation = RR/PV
40 Number of Distinct Categories = 1.41(PV/RR)
0.1 Tolerance = USL-LSL
0.81042 Precision/Tolerance Ratio = RR/(USL-LSL)

Using last column 'Part SN' for Part.

Variance Components for Gauge R&R

Component Var Component % of Total
Gauge R&R 0.00018244 0.12
Repeatability 0.00016879 0.11
Reproducibility 0.00001365 0.0089
Part-to-Part 0.15375831 99.88 +++++++++



Re: % Gauge R&R or Precision-to-Tolerance ratio

Dear @caroljackson ,

I would like too introduce you to my friend Donald Wheeler. (I think of him as a friend, he likely has not idea who I am). 

I could restate the problem as he puts it, or just post the paper here:

The proportions, following the AIAG procedure, which JMP follows exactly, aren't really proportions. So it's possible to have both good, marginal and acceptable results simultaneously.  


I highly recommend reading the paper in the link; however, you can't un-know the problem if you do, so read it at the peril of your bliss. 


Best regards,




JMP Systems Engineer, Pharm and BioPharm Sciences
Level VII

Re: % Gauge R&R or Precision-to-Tolerance ratio

Ans to add to Byron's suggestion, get Wheeler and Lyday's book Evaluating the Measurement Process.

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