Gage R&R: Nested vs Crossed vs Nested Then Crossed vs Crossed then Nested

[#1]

Hi,

I am running a Gage R&R study with 2 factors (Operator and Location), 3 different parts and 3 repetition per part. Operator and Location are nested. This means each location has 2 different operators but the parts are the same. This mean that parts has been moved from one location to the other to be tested by different operators. What option should I use? I would say it is nested then crossed since operator and location are nested but sample and operator with location is crossed. Am I right?

[#2 · Accepted solution]

Hi @jp2,

Concerning your problem, I would also have the same response as you have : your problem seems to involve nested then crossed factors.
One option to see which model type sounds reasonable is to launch the Variability Chart platform, and continue the Gage R&R analysis in the two possible models: Nested then Crossed or Crossed then Nested (full crossed or full nested won't be of interest here), and look at which interactions are present in the Gauge R&R panel (see images).

You can see that interactions present in the Nested+Crossed do correspond to what you can effectively measure : Part x Operator and Location x Part (since all combinations are done for these two interaction terms).
In the Crossed+Nested model, the interaction Operator x Location is mentioned, but is in fact not fully estimable, since not every operator will face the two possible locations.

You can have a look and test these options (scripts saved) with the test dataset I created for your case.

Hope this help you,

[#3]

I think if you enter the factors in this order, Location > Operator > Part, then the Nested and Crossed option should be valid.

[#4]

Hi,

Thanks for the response. I have a question/concern about introducing factors. What would be the difference between your proposal and the scenario of only declaring as factor Location and Operator and inserting Sample/Part variable under Sample box while designing the gauge r&r experiment and selecting nested as gauge option? They should be the same right?

Thanks again

Juan

[#5]

Please see the documentation about launching this platform in case your question is about which analysis role should be used with your variables.

[#6]

First welcome to the community.  You are correct, Operator is nested in Location, Operator and parts are crossed and measurements are nested in Op/Parts.

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