B

**Re: Validation of Gauge R&R program**

I try to calibrate one Gage R&R variable MSA sheet posted in this site and resulting R&R is not the same with Ford standards.

I try to analyze the K1, K2, K3 constants used and I found out the constants in the MSA tested sheet is using 5.15 instead of 6 (Ford is using Six sigma for K1,K2 constants in the calibration sheet). Instead of K1=5.15/d2, Ford calibration is using 6/d2 for the standard deviation(six sigma standard).I have try to fix the constants the results are ok.

Attached is the corrected and calibrated sheet with Ford standards. Thank you Mr. Atkins for the useful validation program.

I try to analyze the K1, K2, K3 constants used and I found out the constants in the MSA tested sheet is using 5.15 instead of 6 (Ford is using Six sigma for K1,K2 constants in the calibration sheet). Instead of K1=5.15/d2, Ford calibration is using 6/d2 for the standard deviation(six sigma standard).I have try to fix the constants the results are ok.

Attached is the corrected and calibrated sheet with Ford standards. Thank you Mr. Atkins for the useful validation program.

Page vi of MSA 3rd:

**NOTE: Regarding the use of the GRR standard deviation**

Historically, by convention, a 99% spread has been used to represent the "full" spread of measurement error, represented by a 5.15 multiplying factor...

If the reader chooses to increase the coverage level, or spread, of the total measurement variation to 99.73%, please use 6 as a multiplier in place of 5.15 in the calculations.

Just means that 5.15 and 6 are both correct to MSA 3rd as long as you know the significance.