# Gage R and R method valid?

#### Jay Kay

##### Registered
Hi,
I have been told to use this methodology, from what I gather this is the most basic method of GRR using only AV and EV and GRR = SQRT(AV^2 + EV^2). Is this a valid methodology reporting only three metrics AV, EV, GRR? I don't believe this the the full Average / Range method....

My second question is, I can't find the reference for the values they claim to use for the constants. The claim is that it is industry standard to use the below tables, notably d4= 2.57 (3 trials) or 3.27 for (2 trials) , k1 =3.05(3 trials) , 4.56 for (2 trials) , k2= 2.7(3 trial) , 3.65 for (2 trials). From my limited understanding there are two references the SPC manual and the MSA manual each having different values, is there any page or image of the page that these numbers come from?

Thanks again

 No of Trials D4 2 3.27 3 2.57

 No of Trials K2 for CI 90%, 95%, 99% Ind Std 2 Same as for K1 3.65 3 Same as for K1 2.7

 Measurement Capability Study Equipment Variation EV (Repeatability) _ = K1 * R(Avg of Avg Ranges) _ = Operator/ Appraiser Variation AV (Reproducibility) _ = {(XDIFF x K2)^2 - (EV^2/nt)}^1/2 Total Repeatability and Reproducibility Variation (R&R) = SQRT[Repeatability^2 + Reproducibility^2] = GRR reported as % of tolerance

#### Miner

##### Forum Moderator
Q1 - The Average/Range method with only provide the EV/AV/Total R&R standard deviations plus the associated metrics (i.e., %SV, %Tolerance, ndc). You need to use the ANOVA method to obtain the Operator x Part interaction.

Q2 - What industry? Only the USA automotive industry has a "standard." The AIAG MSA manual, 4th edition is the standard for MSA. The AIAG SPC manual is the wrong reference for MSA. any constants from that manual would only apply for SPC. Attached are the constants from the AIAG MSA manual 4th edition. I copied these from my GRR template which I verified using the Ford GRR validation data set as my manual is at home. Sorry for not copying the actual manual, but I left that in my home office.

#### Jay Kay

##### Registered
Gotcha! Much appreciated.
By chance at your convenience do you have any recommended templates.
Either way thank you.

Thank you!