New MSA file using ANOVA - January 2010

I don't know if this is the t-value riosimbolon mentioned, but the 1.662 can be found in your "MSA 3rd Ed with ANOVA.xls" (Intro to Measurement System Analysis (MSA) of Continuous Data – Part 5b: R&R), sheet "Stability", cell U43 (called "t_critical alpha=.05" in U42).

According to the MSA manual the critical t-value should be derived using
t^(-1)_{nu, 1-alpha/2}
(1-alpha/2)-quantile of the t-distribution with "nu" degrees of freedom, "nu" from table C1 (appendix C) in MSA 3rd (formula: see p.89 in MSA 3rd and p94 in MSA4th, resp.)

Table C1 does provide "nu"-numbers for a maximum of m=20 readings within a subgroup and a maximum of g=20 subgroups. At the bottom of the table it is stated that further "nu"-values could be build by using cd (constant difference). For a subgroup sample size of m=5 readings, the "nu"-value for g=20 subgroups is 72.7 and the cd=3.623. To obtain the "nu"-value for g=25 subgroups cd have to be added 5 times to the g=20-subgroups-"nu"-value (because 25 = 20 + 5 subgroups):
nu = 72.7 + 5*3.623 = 90.815

1-alpha/2 = 0.975 (for alpha=5%)

The critical t-value for the bias test with m=5 readings, g=20 subgroups and alpha=5% is given by
t^(-1)_{nu, 1-alpha/2} = t^(-1)_{90.815, 0.975} = 1.9864

But in the Excel file 1.662 is presented as the critical t-value. If alpha is set to 10%, this would be the correct value:
t^(-1)_{nu, 1-alpha/2} = t^(-1)_{90.815, 0.95} = 1.6618
(checked with R and Minitab)

Maybe this occurs due to Excel's use of alpha-values within the function TINV (see "A one-tailed t-value..." on TINV function) which differs from the usual behaviour of statistical software packages?

Best regards,

Barbara

Thank you very much. For be learing MSA, this is the most comprehensive I had seen before. Thank you!

Re: New MSA 4th Ed file using ANOVA - September 2013

After several requests, I have updated my MSA - ANOVA file to the 4th Edition. I included the data sets used in the manual where applicable. The Bias and Linearity tabs include all of the 4th edition changes. However, I made selective changes to the R&R tab. I added the option to use known process variation rather than relying solely on the study variation. I did not add the option to use Ppk. I had limited time, and if you have Ppk, you also have the process variation. I also did not add the multitude of graphs. Frankly, most where simply variants of the existing graphs (i.e., stacked versus unstacked) or in my experience were of limited value.

The Excel file, named MSA 4th Ed with ANOVA.xlsx, is good for me to learn how to do variable MSA study with ANOVA. But in the file I cannot find the sheet labeled "Graph Worksheet" which is used to format the results in order to generate the graphs summary as shown in instructions tab. May I know where the "Grsph Worksheet" is or let me how to do it to learn more graph analysis? Thanks!

I hid the tab to prevent accidental modification of the formulae. Just unhide the tabs.

I got it to unhide the sheet. It is useful for me to learn step by step how to do the graph analysis. Thanks!

I already downloaded, I tried that Excel-Anova-program, but how use it if there are more than 3 appraisal,

Rio BP Simbolon said:

I already downloaded, I tried that Excel-Anova-program, but how use it if there are more than 3 appraisal,

Click to expand...

There shouldn't be a need to use more than three operators. The idea is to select operators who represent the skills of a typical production user of the device, not to test everyone who might use it.

Re: New MSA file using ANOVA

Miner, which do you prefer Minitab or Excel?

Regards,
Optomist 1

Minitab, definitely.