# %GRR tolerance analysis [GRR/(tolerance/6)]

#### MrsBlue

##### Registered
Hello!
Hope all has been keeping well!

I need some help to interpret an example of GRR results below.
I have always refer to the %GRR under the total variation analysis, and that result here shows 9.88% which is acceptable (< 10%).

How about the %GRR under the tolerance analysis [GRR/(tolerance/6)], which shows 15.83%? Does this need to fulfill the acceptance criteria of <10%?
How to interpret this result?
Any help or guidance is greatly appreciated.

Many thanks!

(I am unable to insert an image here, so I have manually type the formula & result into a table.)

 Measurement Unit Analysis​ % Total Variation Analysis​ % Tolerance Analysis​ Repeatability - Equipment Variation (EV) EV = 0.00154 %EVv = 100 x [EV/TV] = 8.22% %EVt = 100 x [EV/(Tolerance/6)] = 13.17% Reproducibility - Appraiser Variation (AV) AV = 0.00103 %AVv = 100 x [AV/TV] = 5.49% %AVt = 100 x [AV/(Tolerance/6)] = 8.79% Repeatability & Reproducibility (GRR) GRR = 0.00185 %GRRv = 100 x [GRR/TV] = 9.88% %GRRt = 100 x [GRR/(Tolerance/6)] = 15.83% Part Variation (PV) PV = 0.01860 %PVv = 100 x [PV/TV] = 99.51% %Pvt = 100 x [PV/(Tolerance/6)] = 159.40% Total Variation (TV) TV = 0.01869 ndc = 1.41 x [PV/GRR] = 14

#### Miner

##### Forum Moderator
It depends on the intended use for the measurement device. If you intend to use it for inspection to a tolerance, % Tolerance is the appropriate metric and the other metrics can be ignored. Whether 15.83% is acceptable or not depends on your situation. The MSA manual clearly states that results between 10% and 30% might be accepted given certain circumstances. If the measurement device will be used for SPC then %Total Variation should be used, and %Tolerance can be ignored. The only time when you should consider both metrics is when the measurement device will be used for both inspection and for SPC.

#### MrsBlue

##### Registered
@Miner Many thanks for taking time to reply! Appreciate it.
Wishing you Merry Christmas and Happy New Year!!