How to determine the values of k1, k2, k3 in Gage R&R (2024)

hi all.. have smtn to ask u all..

how to determine the values k1, k2,k3?
is there a standard value for them?

how to determine which one to use in a gr&r study? based on number of operators? number of trials?

Thanks..

k1,k2,k3

You can take the examples given in the MSA manual.

k1 is the constant in relation to the number of trials in the study.
2 trials 0,8862
3 trials 0,5908

k2 is the constant in relation to the number of appraisers in the study.
2 operators 0,7071
3 operators 0,5231

k3 is the constant in relation to the number of parts in the study.
Parts K3
2 0,7071
3 0,5231
4 0,4467
5 0,4030
6 0,3742
7 0,3534
8 0,3375
9 0,3249
10 0,3146

For further details, See MSA manual.

Best regards,

Antoine

Re: k1,k2,k3

Hi,
When I review some of the excel sheets, softwares, and AIAG MSA, i found 2 kind of K1, K2, K3 values.
Eg:
According to several softwares and excel files (minitab, spc for excel) k1 is:

Trials K1
2 4.5600
3 3.0500

According to the MSA handbook (3rd edition, page 114), and some softwares K1 is

Trials K1
2 0,8862
3 0,5908

Do you happen to know the reason of that???

Thank you,

Welcome to the cove.

The difference you have found is due to the different approach in the MSA manual ( difference between version 2 and version 3 of the MSA manual )

Hope this helps,

Antoine

I'm ok with the answer but what is the difference between the old system and the new? because the constant value are really differente and change considerably the result?

Anyone have an answer to this?

Alex.G said:

I'm ok with the answer but what is the difference between the old system and the new? because the constant value are really differente and change considerably the result?

Anyone have an answer to this?

Click to expand...

The answer lies in the different equations used in Version 2 and Version 3.

You cannot just simply substitute the Version 3 K values in an Version 2 worksheet.

Have a look at discussions in this thread: and Warning as to MSA 3rd edition worksheets

I still don't clearly see where the problem is from, PV or TV?
I review my spreadsheet and I tried to insert the values from the MSA reference manual 3rd edition p 113, with my spreadsheet I get exactly the same value as p114, my excel is wrong or not? did they made a mistake in the book?

My excel used the old constant values before and I only change it with the new value in 3rd edition, so i didn't change the way to calculate.

below is my excel :

I came to this question few years ago and had done some further study on them.......We need to use the Appendix C - d2 table for K constants calculation.

K1 - Used for Repeatability, Equipment Variation (EV) calculation
Find the d2 from Appendix C - d2 table,
focus on the subgroup size(m) for

we used in GR&R study, number of subgroups (g) for

we used in GR&R study. If the parts x number of operator greater then 20, find the d2 at the bottom of the table.
K1 = 1/d2

K2 - Used for Reproducibility, Appraiser Variation (AV) calculation
Find the d2 from Appendix C - d2 table,
focus on the subgroup size(m) for

we used in GR&R study, number of subgroups (g) is set as 1 as there is only one range calculation in this study.
K2 = 1/d2

K3 - Used for Part Variation (PV) calculation
Find the d2 from Appendix C - d2 table,
focus on the subgroup size(m) for

we used in GR&R study, number of subgroups (g) is set as 1 as there is only one range calculation in this study.
K3 = 1/d2

AIAG MSA guideline used formula K = 1/d2, all the sigma (EV, AV and PV) calculated used the original formula with K value replaced and %PT Ratio = (100x 5.15 x sigma R&R)/product specification.

Larry B. Barrentine used formula K = 5.15/d2, all the sigma (EV, AV and PV) calculated used the original formula with K value replaced

and %PT Ratio = (100 x 5.15 x sigma R&R)/product specification.

Noted: We do not use the factor 5.15 or 6 in GR&R% calculation (compare to process variation), it is only apply in PT Ratio calculation (compare to product specification)