When we took the example of Gage R&R using ANOVA Method we selected the Crossed Gage R&R study.
Here on this slide
let's understand the difference between the Crossed Gage R&R study and the Nested Gage R&R study.
When we do Crossed Gage R&R study what we do is we take three Operators, we take 10 Parts
and we ask each operator to take three measurements.
So with that we end up with 90 readings.
So let me put it here.
So we have three operators or the three appraisers- appraiser A, appraiser B, appraiser C. Each of
these appraisers look at each of these ten pieces, so I have piece number 1, 2, 3, 4, 5 and so on.
Let's put it five here on this picture to make it simple.
So the appraiser one looks at Part number one, two, three, four, and five, takes the reading, takes the reading
three times.
So reading number one, reading number two, reading number three,
this is by appraiser A.
Then the same ten Parts in this simple example we have taken five here, the same five Parts
appraiser B also looks into that, appraiser B also measures that, appraiser C also measures these pieces.
So each of these three operators or the appraisers measure ten Parts three times each leading to 90 reading
that's what you do in Crossed
Gage R&R study.
But what happens if the test you are doing or the measurement which you are taking is a destructive
one.
The example of destructive could be the paint peeling strength, you peel the paint and see how much
stronger that is. You can not do the same
test number of times.
One operator cannot do the same test three times or even three Operators cannot do this this because
the item will get destroyed.
Let's say if you want to find out the breaking strength of a piece, so if you take piece number one, operator
number A find out breaking strength of that,
that's it.
Now the operator A cannot find the breaking strength of that piece number one second time ,third time.
So here now what you will do is you will take 90 pieces and 90 pieces will be tested by these three
operators or appraisers and they will record the value.
So here in this case in Nested one you will have appraiser A,
we look at Part number one, Part number two, Part number three and so on.
And same thing with the appraiser B, and appraiser C also.
So none of these Parts will be re-tested by another operator.
So that's the key difference between Crossed and Nested Gage R&R. Crossed one is used where the
test is Nondestructive, Nested one is used where the test is Destructiv, where only 1 operator measures
each Part because the Part gets destroyed.
So this complete the difference between Crossed and Nested Gage R&R study.